Tire monitoring with passive and active modes

ABSTRACT

Movable vehicular assembly including an electricity generating system includes a movable substrate such as a tire, a power generating system arranged on, in connection with or within the substrate and to generate energy from movement of the substrate, and a circuit coupled to the power generating system and including an energy storage device. The circuit is operable in an active mode when the substrate moves and the power generating system generates energy or the energy storage device contains energy for powering the circuit and in a passive mode when the substrate is not moving and the energy storage device does not contain sufficient energy to power the circuit. The circuit receives power to operate in the passive mode from a signal received by the circuit. Components which may be part of the circuit include a surface-acoustic-wave device and a radio-frequency identification device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application

1. a continuation-in-part (CIP) of U.S. patent application Ser. No.10/642,028 filed Aug. 15, 2003, now U.S. Pat. No. 7,253,725, whichclaims priority under 35 U.S.C. §119(e) of U.S. provisional patentapplication Ser. No. 60/415,862 filed Oct. 3, 2002, now expired;

2. a CIP of U.S. patent application Ser. No. 10/931,288 filed Aug. 31,2004, now U.S. Pat. No. 7,164,117, which is a

-   -   A. a CIP of U.S. patent application Ser. No. 10/613,453 filed        Jul. 3, 2003, now U.S. Pat. No. 6,850,824, which is a        continuation of U.S. patent application Ser. No. 10/188,673        filed Jul. 3, 2002, now U.S. Pat. No. 6,738,697, which is:        -   1) a CIP of U.S. patent application Ser. No. 10/079,065            filed Feb. 19, 2002, now U.S. Pat. No. 6,662,642, which is:            -   a) a CIP of U.S. patent application Ser. No. 09/765,558                filed Jan. 19, 2001, now U.S. Pat. No. 6,748,797, which                claims priority under 35 U.S.C. §119(e) of U.S.                provisional patent application Ser. No. 60/231,378 filed                Sep. 8, 2000, now expired; and            -   b) claims priority under 35 U.S.C. §119(e) of U.S.                provisional patent application Ser. No. 60/269,415 filed                Feb. 16, 2001, now expired, U.S. provisional patent                application Ser. No. 60/291,511 filed May 16, 2001, now                expired, and U.S. provisional patent application Ser.                No. 60/304,013 filed Jul. 9, 2001, now expired; and    -   B. a CIP of U.S. patent application Ser. No. 10/805,903 filed        Mar. 22, 2004, now U.S. Pat. No. 7,050,897, which is a CIP of        U.S. patent application Ser. No. 10/188,673, filed Jul. 3, 2002,        now U.S. Pat. No. 6,738,697;

3. a CIP of U.S. patent application Ser. No. 11/082,739 filed Mar. 17,2005, now U.S. Pat. No. 7,421,321, which is a CIP of U.S. patentapplication Ser. No. 10/701,361, filed Nov. 4, 2003, now U.S. Pat. No.6,988,026, which is:

-   -   A. a CIP of U.S. patent application Ser. No. 10/613,453 filed        Jul. 3, 2003, now U.S. Pat. No. 6,850,824;    -   B. a CIP of U.S. patent application Ser. No. 09/765,558 filed        Jan. 19, 2001, now U.S. Pat. No. 6,748,797;    -   C. a CIP of U.S. patent application Ser. No. 10/642,028 filed        Aug. 15, 2003, now U.S. Pat. No. 7,253,725; and    -   D. a CIP of U.S. patent application Ser. No. 10/079,065 filed        Feb. 19, 2002, now U.S. Pat. No. 6,662,642;

4. a CIP of U.S. patent application Ser. No. 11/220,139 filed Sep. 6,2005, now U.S. Pat. No. 7,103,460, which is a CIP of U.S. patentapplication Ser. No. 11/120,065 filed May 2, 2005, now abandoned;

5. a CIP of U.S. patent application Ser. No. 11/379,078 filed Apr. 18,2006, now U.S. Pat. No. 7,379,800;

6. a CIP of U.S. patent application Ser. No. 11/381,609 filed May 4,2006, now U.S. Pat. No. 7,408,453;

7. a CIP of U.S. patent application Ser. No. 11/382,091 filed May 8,2006 U.S. Pat. No. 7,549,327;

8. a CIP of U.S. patent application Ser. No. 11/421,500 filed Jun. 1,2006 U.S. Pat. No. 7,672,756; and

9. a CIP of U.S. patent application Ser. No. 11/428,498 filed Jul. 3,2006.

This application contains common subject matter as U.S. patentapplication Ser. No. 10/940,881 filed Sep. 13, 2004 and Ser. No.11/278,188 filed Mar. 31, 2006.

All of the references, patents and patent applications that are referredto herein and in the parent applications are incorporated by referencein their entirety as if they had each been set forth herein in full.Note that this application is one in a series of applications coveringsafety and other systems for vehicles and other uses. The disclosureherein goes beyond that needed to support the claims of the particularinvention set forth herein. This is not to be construed that theinventor is thereby releasing the unclaimed disclosure and subjectmatter into the public domain. Rather, it is intended that patentapplications have been or will be filed to cover all of the subjectmatter disclosed below and in the current assignee's granted and pendingapplications. Also please note that the terms frequently used below “theinvention” or “this invention” is not meant to be construed that thereis only one invention being discussed. Instead, when the terms “theinvention” or “this invention” are used, it is referring to theparticular invention being discussed in the paragraph where the term isused.

FIELD OF THE INVENTION

The present invention relates generally to tire monitoring techniquesand more particularly to tire monitoring systems and methods whereinenergy to power one or more tire condition sensors is generated uponrotation of the tire.

There are numerous methods and components described and disclosedherein. Many combinations of these methods and components are describedbut in order to conserve space the inventor has not described allcombinations and permutations of these methods and components, however,the inventor intends that each and every such combination andpermutation is an invention to be considered disclosed by thisdisclosure. The inventor further intends to file continuation andcontinuation-in-part applications to cover many of these combinationsand permutations, if necessary.

BACKGROUND OF THE INVENTION

A detailed background of the invention is found in the parentapplication, U.S. patent application Ser. No. 11/220,139, incorporatedby reference herein.

The definitions set forth in section 5.0 of the Background of theInvention section of the '139 application are also incorporated byreference herein.

All of the patents, patent applications, technical papers and otherreferences referenced in the '139 application and herein areincorporated herein by reference in their entirety.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide new and improvedtire monitoring techniques.

It is another object of the present invention to provide new andimproved tire monitoring systems and methods wherein energy to power oneor more tire condition sensors is generated upon rotation of the tire.

It is still another object of the invention to provide a tire monitorsystem and method with both an active mode and a passive mode tooptimize the use of energy available for tire monitoring.

In order to achieve these objects and others, a movable vehicularassembly including an electricity generating system in accordance withthe invention includes a movable substrate such as a tire, a powergenerating system arranged on, in connection with or within thesubstrate and to generate energy from movement of the substrate, and acircuit coupled to the power generating system and including an energystorage device. The circuit is operable in an active mode when thesubstrate moves and the power generating system generates energy or theenergy storage device contains energy for powering the circuit and in apassive mode when the substrate is not moving and the energy storagedevice does not contain sufficient energy to power the circuit. Thecircuit receives power to operate in the passive mode from a signalreceived by the circuit. Components which may be part of the circuitinclude a surface-acoustic-wave device and a radio-frequencyidentification device.

Numerous variations and constructions of the circuit are possibleincluding arranging the circuit to provide data about a property of thesubstrate and with one or more wireless transmission components capableof receiving a signal for powering the circuit in the passive mode.Transmission of a signal from the wireless component(s) in the passivemode may, in some embodiments, be considered indicative of a conditionrelating to the property.

When the substrate is a tire, the circuit can include a pressure sensorfor generating data about the pressure in the tire such that the dataabout the property of the tire is its pressure. The power generatingsystem would generate power upon rotation of the tire, and in morespecific embodiments, upon deflection or flexure of the tire tread orflexible side walls. Transmission of a signal from the wirelesstransmission component(s) in the passive mode may be indicative of apressure in the tire below a threshold. As such, only when the tirepressure is below a threshold, the signal will be transmitted, therebyoptimizing the available energy to the circuit. Thus, when the vehicleis stationary and there is insufficient power in the energy storagedevice for full use of the circuit, if the tire's pressure falls belowthe threshold, a signal relating to the pressure will be transmitted.

In one embodiment, the circuit includes at least one wirelesstransmission component for receiving a signal for powering the circuitin the passive mode and at least one sensor for generating or modifyinga signal received by the wireless transmission component as a functionof a sensed property. The generated or modified signal may be indicativeof the sensed property.

In one embodiment, the circuit generates or modifies a signal whichenables a determination of at least one property of the tire, e.g.,pressure, temperature, acceleration and deformation, and optionallywirelessly transmits the signal along with a preferably uniqueidentification of the tire. This is useful for most vehicles which havemultiple tires.

The wireless transmission component(s) may be arranged to wirelesslytransmit signals only when energy available to the circuit exceeds athreshold.

The circuit may include one or more sensors arranged to generate ormodify a plurality of signals which enable a determination of aplurality of properties of the tire. The wireless transmissioncomponent(s) may be arranged to wirelessly transmit one or more of thesignals based on the amount of energy available to the circuit.

The circuit may include one or more sensors arranged to measure ordetermine a property of the tire, at least one wireless transmissioncomponent arranged to receive an interrogation signal and cause eachsensor to generate a return signal and a circulator arranged between asensor and the wireless transmission component to boost the returnsignal. In a related embodiment, the circuit includes one or moresensors arranged to modify a signal which enables a determination of aproperty of the tire, at least one wireless transmission componentarranged to receive an interrogation signal and cause each sensor tomodify the interrogation signal and a circulator arranged between asensor and a wireless transmission component to boost the interrogationsignal being directed to that sensor and the modified interrogationsignal being directed from that sensor.

Another variation of the circuit includes at least one pressure sensorarranged to generate or modify a first signal which enables adetermination of pressure of the tire, at least one additional sensorarranged to generate or modify a second signal which enables adetermination of another property of the tire, and at least one wirelesstransmission component arranged to wirelessly transmit the first signalwhen the circuit is in the passive mode and optionally transmit thesecond signal when the circuit is in the active mode.

Yet another variation of the circuit includes at least one pressuresensor arranged to generate or modify a signal which enables adetermination of pressure of the tire and at least one wirelesstransmission component arranged to wirelessly transmit the signal atdifferent times spaced apart from one another an amount of timedependent on the amount of energy available to the circuit. When moreenergy is available, the interval between transmissions is less incomparison to a situation where less energy is available.

Still another variation of the circuit includes a pressure sensorarranged to generate or modify a signal which enables a determination ofpressure of the tire, a wireless transmission component arranged towirelessly transmit the signal, and a pressure-activated switchinterposed between the pressure sensor and the wireless transmissioncomponent and having a closed position only when pressure in the tire isbelow a threshold and the circuit is in the passive mode. The circuitoptionally includes an additional switch interposed between the pressuresensor and the wireless transmission component and which has a closedposition only when the circuit is in the active mode.

Various constructions of the power generating system are possible. Inone construction, the power generating system includes a pad made frompiezoelectric material and arranged to flex upon rotation of the tire.Flexing of the pad causes a charge to appear on opposite sides thereofthereby creating a voltage which charges the energy storage device. Thepad may be attached to an inner surface of the substrate adjacent to thetread. The pad may include a plurality of layers of piezoelectricmaterial and/or a plurality of sections of piezoelectric material joinedtogether to form a belt stretching around an inner circumference of thesubstrate.

A method for monitoring a tire in accordance with the invention includesarranging a monitoring system on the tire which generates or modifies asignal which enables a determination of at least one property of thetire and provides a wireless transmission of the generated or modifiedsignal, generating energy to power the monitoring system from rotationof the tire, storing energy to power the monitoring system when the tireis not rotating, and directing an interrogation signal to the monitoringsystem to obtain in response, the wireless transmission of the signalgenerated or modified by the monitoring system. When the tire isrotating or there is sufficient stored energy, the monitoring system isoperating in an active mode and when the tire is not rotating and thereis insufficient stored energy to power to monitoring system, themonitoring system is in a passive mode and energy to power themonitoring system is provided from the interrogation signal.

The monitoring system may be attached to a side wall or tread of thetire. Energy to power the monitoring system may be generated upondeflection or flexure of a tire tread or side walls of the tire, e.g.,via a PVDF pad. The monitoring system may be constructed to transmit thegenerated or modified signal along with an identification of the tire,the identification being transmitted only when sufficient power isavailable to the monitoring system. Properties of the tire determinablefrom the signal provided by the tire monitoring system include pressureof the tire, temperature of the tire, and acceleration or deformation ofa tread of the tire when the tire is rotating. The monitoring system maybe constructed to transmit the generated or modified signal in thepassive mode whenever an interrogation signal is received only whenstored energy available to the monitoring system exceeds a threshold.The monitoring system may be constructed to generate or modify aplurality of signals which enable a determination of a plurality ofproperties of the tire. In this case, the monitoring system can beprogrammed to select which of the plurality of signals to transmit basedon the amount of energy available to the monitoring system. Themonitoring system can be constructed to transmit the generated ormodified signal at different times spaced apart from one another anamount of time dependent on the amount of energy available to themonitoring system. The monitoring system may include a pressure sensorarranged to generate or modify a signal which enables a determination ofpressure of the tire and a wireless transmission component arranged towirelessly transmit the signal. A pressure-activated switch can bearranged between the pressure sensor and the wireless transmissioncomponent and which has a closed position only when pressure in the tireis below a threshold and the monitoring system is in the passive mode.Optionally, an additional switch can be arranged between the pressuresensor and the wireless transmission component and which has a closedposition only when the monitoring system is in the active mode.

Other objects and advantages of the present claimed invention andinventions disclosed below are set forth in the '139 application andothers will become apparent from the following description of thepreferred embodiments taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the systemsdeveloped or adapted using the teachings of these inventions and are notmeant to limit the scope of the invention as encompassed by the claims.

FIG. 1 is a schematic illustration of a generalized component withseveral signals being emitted and transmitted along a variety of paths,sensed by a variety of sensors and analyzed by the diagnostic module inaccordance with the invention and for use in a method in accordance withthe invention.

FIG. 2 is a schematic of one pattern recognition methodology known as aneural network which may be used in a method in accordance with theinvention.

FIG. 3 is a schematic of a vehicle with several components and severalsensors and a total vehicle diagnostic system in accordance with theinvention utilizing a diagnostic module in accordance with the inventionand which may be used in a method in accordance with the invention.

FIG. 4 is a flow diagram of information flowing from various sensorsonto the vehicle data bus and thereby into the diagnostic module inaccordance with the invention with outputs to a display for notifyingthe driver, and to the vehicle cellular phone for notifying anotherperson, of a potential component failure.

FIG. 5 is an overhead view of a roadway with vehicles and a SAW roadtemperature and humidity monitoring sensor.

FIG. 5A is a detail drawing of the monitoring sensor of FIG. 5.

FIG. 6 is a perspective view of a SAW system for locating a vehicle on aroadway, and on the earth surface if accurate maps are available, andalso illustrates the use of a SAW transponder in the license plate forthe location of preceding vehicles and preventing rear end impacts.

FIG. 7 is a partial cutaway view of a section of a fluid reservoir witha SAW fluid pressure and temperature sensor for monitoring oil, water,or other fluid pressure.

FIG. 8 is a perspective view of a vehicle suspension system with SAWload sensors.

FIG. 8A is a cross section detail view of a vehicle spring and shockabsorber system with a SAW torque sensor system mounted for measuringthe stress in the vehicle spring of the suspension system of FIG. 8.

FIG. 8B is a detail view of a SAW torque sensor and shaft compressionsensor arrangement for use with the arrangement of FIG. 8.

FIG. 9 is a cutaway view of a vehicle showing possible mountinglocations for vehicle interior temperature, humidity, carbon dioxide,carbon monoxide, alcohol or other chemical or physical propertymeasuring sensors.

FIG. 10A is a perspective view of a SAW tilt sensor using four SAWassemblies for tilt measurement and one for temperature.

FIG. 10B is a top view of a SAW tilt sensor using three SAW assembliesfor tilt measurement each one of which can also measure temperature.

FIG. 11 is a perspective exploded view of a SAW crash sensor for sensingfrontal, side or rear crashes.

FIG. 12 is a perspective view with portions cutaway of a SAW basedvehicle gas gage.

FIG. 12A is a top detailed view of a SAW pressure and temperaturemonitor for use in the system of FIG. 12.

FIG. 13A is a schematic of a prior art deployment scheme for an airbagmodule.

FIG. 13B is a schematic of a deployment scheme for an airbag module inaccordance with the invention.

FIG. 14 is a schematic of a vehicle with several accelerometers and/orgyroscopes at preferred locations in the vehicle.

FIG. 15A illustrates a driver with a timed RFID standing with groceriesby a closed trunk.

FIG. 15B illustrates the driver with the timed RFID 5 seconds after thetrunk has been opened.

FIG. 15C illustrates a trunk opening arrangement for a vehicle inaccordance with the invention.

FIG. 16A is a view of a view of a SAW switch sensor for mounting on orwithin a surface such as a vehicle armrest.

FIG. 16B is a detailed perspective view of the device of FIG. 16A withthe force-transmitting member rendered transparent.

FIG. 16C is a detailed perspective view of an alternate SAW device foruse in FIGS. 16A and 16B showing the use of one of two possibleswitches, one that activates the SAW and the other that suppresses theSAW.

FIG. 16D is a schematic of a RFID controlled by a switch.

FIG. 16E is a schematic of a SAW device controlled by a switch.

FIG. 16F is a schematic of a backscatter antenna which is controlled bya switch.

FIG. 16G is a schematic of circuit for a monitoring system in accordancewith the invention which has two switches.

FIG. 17A is a detailed perspective view of a polymer and mass on SAWaccelerometer for use in crash sensors, vehicle navigation, etc.

FIG. 17B is a detailed perspective view of a normal mass on SAWaccelerometer for use in crash sensors, vehicle navigation, etc.

FIG. 18 is a view of a prior art SAW gyroscope that can be used withthis invention.

FIGS. 19A, 19B and 19C are block diagrams of three interrogators thatcan be used with this invention to interrogate several differentdevices.

FIG. 20A is a top view of a system for obtaining information about avehicle or a component therein, specifically information about thetires, such as pressure and/or temperature thereof.

FIG. 20B is a side view of the vehicle shown in FIG. 20A.

FIG. 20C is a schematic of the system shown in FIGS. 20A and 20B.

FIG. 21 is a top view of an alternate system for obtaining informationabout the tires of a vehicle.

FIG. 22 is a plot which is useful to illustrate the interrogator burstpulse determination for interrogating SAW devices.

FIG. 23 illustrates the shape of an echo pulse on input to thequadrature demodulator from a SAW device.

FIG. 24 illustrates the relationship between the burst and echo pulsesfor a 4 echo pulse SAW sensor.

FIG. 25 illustrates the paths taken by various surface waves on a tiretemperature and pressure monitoring device of one or more of theinventions disclosed herein.

FIG. 26 is an illustration of a SAW tire temperature and pressuremonitoring device.

FIG. 27 is a side view of the SAW device of FIG. 26.

FIGS. 28A and 28B are schematic drawings showing two possible antennalayouts for 18 wheeler truck vehicles that permits the positiveidentification of a tire that is transmitting a signal containingpressure, temperature or other tire information through the use ofmultiple antennas arranged in a geometric pattern to permittriangulation calculations based on the time of arrival or phase of thereceived pulses.

FIG. 29A is a partial cutaway view of a tire pressure monitor using anabsolute pressure measuring SAW device.

FIG. 29B is a partial cutaway view of a tire pressure monitor using adifferential pressure measuring SAW device.

FIG. 30 is a partial cutaway view of an interior SAW tire temperatureand pressure monitor mounted onto and below the valve stem.

FIG. 30A is a sectioned view of the SAW tire pressure and temperaturemonitor of FIG. 30 incorporating an absolute pressure SAW device.

FIG. 30B is a sectioned view of the SAW tire pressure and temperaturemonitor of FIG. 30 incorporating a differential pressure SAW device.

FIG. 31 is a view of an accelerometer-based tire monitor alsoincorporating a SAW pressure and temperature monitor and cemented to theinterior of the tire opposite the tread.

FIG. 31A is a view of an accelerometer-based tire monitor alsoincorporating a SAW pressure and temperature monitor and inserted intothe tire opposite the tread during manufacture.

FIG. 32 is a detailed view of a polymer on SAW pressure sensor.

FIG. 32A is a view of a SAW temperature and pressure monitor on a singleSAW device.

FIG. 32B is a view of an alternate design of a SAW temperature andpressure monitor on a single SAW device.

FIG. 33 is a perspective view of a SAW temperature sensor.

FIG. 33A is a perspective view of a device that can provide twomeasurements of temperature or one of temperature and another of someother physical or chemical property such as pressure or chemicalconcentration.

FIG. 33B is a top view of an alternate SAW device capable of determiningtwo physical or chemical properties such as pressure and temperature.

FIGS. 34 and 34A are views of a prior art SAW accelerometer that can beused for the tire monitor assembly of FIG. 31.

FIG. 35 is a perspective view of a SAW antenna system adapted formounting underneath a vehicle and for communicating with the fourmounted tires.

FIG. 35A is a detail view of an antenna system for use in the system ofFIG. 35.

FIG. 36 is a partial cutaway view of a piezoelectric generator and tiremonitor using PVDF film.

FIG. 36A is a cutaway view of the PVDF sensor of FIG. 36.

FIG. 37 is an alternate arrangement of a SAW tire pressure andtemperature monitor installed in the wheel rim facing inside.

FIG. 38 illustrates an alternate method of applying a force to a SAWpressure sensor from the pressure capsule.

FIG. 38A is a detailed view of FIG. 38 of area 38A.

FIG. 39 is an alternate method of FIG. 38A using a thin film of LithiumNiobate

FIG. 40 illustrates a preferred four pulse design of a tire temperatureand pressure monitor based on SAW.

FIG. 40A illustrates the echo pulse magnitudes from the design of FIG.40.

FIG. 41 illustrates an alternate shorter preferred four pulse design ofa tire temperature and pressure monitor based on SAW.

FIG. 41A illustrates the echo pulse magnitudes from the design of FIG.41

FIG. 42 is a schematic illustration of an arrangement for boostingsignals to and from a SAW device in accordance with the invention.

FIG. 43 is a schematic of a circuit used in the boosting arrangement ofFIG. 42.

FIG. 44 is a block diagram of the components of the circuit shown inFIG. 43.

FIG. 44A is a block diagram of the two-port circular shown in FIG. 42 inwhich a pair of three-port circulators are provided.

FIG. 44B is an exemplifying circuit diagram of a three-port circulatorfor use in the invention.

FIG. 45 is a schematic of a circuit used for charging a capacitor duringmovement of a vehicle which may be used to power the boostingarrangement of FIG. 42.

FIG. 46 is a block diagram of the components of the circuit shown inFIG. 45.

FIG. 47 is a view of a wheel including a tire pumping system inaccordance with the invention.

FIG. 47A is an enlarged view of the tire pumping system shown in FIG.47.

FIG. 47B is an enlarged view of the tire pumping system shown in FIG. 47during a pumping stroke.

FIG. 47C is an enlarged view of an electricity generating system usedfor powering a pump.

FIGS. 48A and 48B show an RFID energy generator.

FIG. 49A shows a front view, partially broken away of a PVDF energygenerator in accordance with the invention.

FIG. 49B is a cross-sectional view of the PVDF energy generator shown inFIG. 49A.

FIG. 50A is a front view of an energy generator based on changes in thedistance between the tire tread and rim.

FIG. 50B shows a view of a first embodiment of a piston assembly of theenergy generator shown in FIG. 50A.

FIG. 50C shows a view of a second embodiment of a piston assembly of theenergy generator shown in FIG. 50A.

FIG. 50D shows a position of the energy generator shown in FIG. 50A whenthe tire is flat.

FIG. 51 is an oscilloscope trace by Transense Technologies, which oneconfirms correspondence between interrogator pulse and voltage at thesaw antenna.

FIG. 52A illustrates an electronic circuit such as used by TransenseTechnologies for their SAW based tire temperature and pressure monitor.

FIG. 52B illustrates an improved electronic circuit for use with an FIDswitch.

FIG. 52C is the timing diagram corresponding to FIG. 52B.

FIG. 53 is an oscillogram of RF pulses, which are radiated theinterrogator.

FIG. 54 show diodes which transpose any signal from the antenna to asupply voltage (approximately 1.2V) for a digital code analyzer andsensor's SPDT switch S1

FIG. 55 shows diode detectors D3 and D4 which transpose signals from theantenna to digital code.

FIG. 56 shows an arrangement for measuring tire temperature inaccordance with a preferred embodiment of the present invention.

FIG. 56A schematically illustrates the elements of a tire temperaturesensor in accordance with the invention.

FIG. 57A shows a thermal emitted radiation detecting device inaccordance with a preferred embodiment of the invention.

FIG. 57B is a cross-sectional, partial view of a tire well of a trucktrailer showing the placement of the thermal emitted radiation detectingdevice shown in FIG. 57A.

FIG. 58 schematically shows a compound Fresnel lens used in the thermalemitted radiation detecting device of FIG. 57A.

FIG. 59 schematically illustrates a circuit for deriving an indicationof a temperature imbalance between two tires using tire temperaturesensor of FIGS. 57A and 57B.

FIG. 60 illustrates another embodiment of the thermal emitted radiationdetector for use in the method and apparatus in accordance with theinvention.

FIG. 61 illustrates another embodiment of the thermal emitted radiationdetector for use in the method and apparatus in accordance with theinvention.

FIG. 62 illustrates another embodiment of the thermal emitted radiationdetector for use in the method and apparatus in accordance with theinvention.

FIG. 63 is a schematic illustration showing a basic apparatus formonitoring tires in accordance with the invention.

FIG. 64 is a schematic illustration showing one basic method formonitoring tires in accordance with the invention.

FIG. 65 is a schematic illustration showing another basic method formonitoring tires in accordance with the invention.

FIG. 66 is a schematic of another embodiment of the invention fordetecting problems with a tire.

FIG. 67 is a table showing temperatures for the differentcircumferential locations of the tire shown in FIG. 63.

FIG. 68 is a side view with parts cutaway and removed of a vehicleshowing the passenger compartment containing a rear facing child seat onthe front passenger seat and a preferred mounting location for anoccupant and rear facing child seat presence detector.

FIG. 69 is a partial cutaway view of a vehicle driver wearing a seatbeltwith SAW force sensors.

FIGS. 70A, 70B, 70C and 70D are different views of an automotiveconnector for use with a coaxial electrical bus for a motor vehicleillustrating the teachings of this invention.

FIG. 71A is a front view of a steering wheel having two generalizedswitches located at 3 and 9 o'clock of the steering wheel rim.

FIG. 71B is a view similar to FIG. 71A with the addition of a thumbswitch option.

FIG. 71C is a rear view of the steering wheel of FIG. 71B with a fingertrigger option.

FIG. 72 illustrates the addition of a mouse type scroll wheel for theleft hand.

FIG. 73 illustrates a strain gage on a bolt weight sensor.

FIGS. 74A, 74B, 74C, 74D and 74E are views of occupant seat weightsensors using a slot spanning SAW strain gage and other strainconcentrating designs.

FIG. 75 is a flow chart of the methods for automatically monitoring avehicular component in accordance with the invention.

FIG. 76 is a schematic illustration of the components used in themethods for automatically monitoring a vehicular component.

FIG. 77 is a side view with parts cutaway and removed showingschematically the interface between the vehicle interior monitoringsystem of this invention and the vehicle cellular communication system.

FIG. 78 is a diagram of one exemplifying embodiment of the invention.

FIG. 79 is a perspective view of a carbon dioxide SAW sensor formounting in the trunk lid for monitoring the inside of the trunk fordetecting trapped children or animals.

FIG. 79A is a detailed view of the SAW carbon dioxide sensor of FIG. 79.

FIG. 80 is a schematic view of overall telematics system in accordancewith the invention.

FIG. 81 is a perspective view of the combination of an occupant positionsensor, diagnostic electronics and power supply and airbag moduledesigned to prevent the deployment of the airbag if the seat isunoccupied.

FIG. 82 shows the application of a preferred implementation of theinvention for mounting on the rear of front seats to provide protectionfor rear seat occupants.

FIG. 83 is another implementation of the invention incorporating theelectronic components into and adjacent the airbag module.

FIGS. 84 and 84A illustrate a dihedral reflector.

FIG. 85 illustrates the reflection pattern from a dihedral reflector inthe azimuth plane.

FIG. 86 illustrates the reflection pattern from a dihedral reflector inthe vertical plane.

FIG. 87 illustrates the angle doubling effect of a dihedral reflectorwhen a polarized wave impinges at an angle.

FIG. 88 is an example of the use of a dihedral reflector for determiningthe position of a vehicle on a roadway.

FIG. 89 shows a dihedral reflector set at 45 degrees to an incidentpolarized radar beam to achieve a 90 degree rotation during reflection.

FIG. 90A is a block diagram of an alternate very low cost low powermethod of making a tire pressure and temperature monitor where theelectronics resides in the tire mounted transceiver.

FIG. 90B is a circuit diagram of an RF operated power supply for thedevice of FIG. 90A.

FIG. 91 is a sketch showing a sensor assembly system in accordance withthe invention.

FIG. 92 is a diagram of a first combination neural network used todiagnose components in accordance with the invention.

FIG. 93 is a diagram of a second combination neural network used todiagnose components in accordance with the invention.

FIG. 94 illustrates a Hall effect based tire pressure monitor utilizinga cantilevered spring to support the moving magnet.

FIG. 94A illustrates a Hall effect based tire pressure monitor utilizinga spring washer to support the moving magnet.

FIG. 95 illustrates the use of dual magnets, one fixed and the otherstationary, permitting a differential measurement.

FIG. 96 illustrates the addition of a magnetic circuit to concentratethe magnetic field lines in the Hall effect sensing element.

FIG. 97 illustrates the addition of a magnetic circuit to concentratethe magnetic field lines in the Hall effect sensing element and the useof an electro magnet adjacent the sensor in place of a magnet on thewheel.

FIG. 98 is a schematic of a system for monitoring a tire in accordancewith the invention.

DETAILED DESCRIPTION OF THE INVENTION 1.1 General Diagnostics andPrognostics

The output of a diagnostic system is generally the present condition ofthe vehicle or component. However the vehicle operator wants to repairthe vehicle or replace the component before it fails, but a diagnosissystem in general does not specify when that will occur. Prognostics isthe process of determining when the vehicle or a component will fail. Atleast one of the inventions disclosed herein in concerned withprognostics. Prognostics can be based on models of vehicle or componentdegradation and the effects of environment and usage. In this regard itis useful to have a quantitative formulation of how the componentdegradation depends on environment, usage and current componentcondition. This formulation may be obtained by monitoring condition,environment and usage level, and by modeling the relationships withstatistical techniques or pattern recognition techniques such as neuralnetworks, combination neural networks and fuzzy logic. In some cases, itcan also be obtained by theoretical methods or from laboratoryexperiments.

A preferred embodiment of the vehicle diagnostic and prognostic unitdescribed below performs the diagnosis and prognostics, i.e., processesthe input from the various sensors, on the vehicle using, for example, aprocessor embodying a pattern recognition technique such as a neuralnetwork. The processor thus receives data or signals from the sensorsand generates an output indicative or representative of the operatingconditions of the vehicle or its component. A signal could thus begenerated indicative of an under-inflated tire, or an overheatingengine.

For the discussion below, the following terms are defined as follows:

The term “component” as used herein generally refers to any part orassembly of parts which is mounted to or a part of a motor vehicle andwhich is capable of emitting a signal representative of its operatingstate. The following is a partial list of general automobile and truckcomponents, the list not being exhaustive:

Engine; transmission; brakes and associated brake assembly; tires;wheel; steering wheel and steering column assembly; water pump;alternator; shock absorber; wheel mounting assembly; radiator; battery;oil pump; fuel pump; air conditioner compressor; differential gearassembly; exhaust system; fan belts; engine valves; steering assembly;vehicle suspension including shock absorbers; vehicle wiring system; andengine cooling fan assembly.

The term “sensor” as used herein generally refers to any measuring,detecting or sensing device mounted on a vehicle or any of itscomponents including new sensors mounted in conjunction with thediagnostic module in accordance with the invention. A partial,non-exhaustive list of sensors that are or can be mounted on anautomobile or truck is:

Airbag crash sensor; microphone; camera; chemical sensor; vapor sensor;antenna, capacitance sensor or other electromagnetic wave sensor; stressor strain sensor; pressure sensor; weight sensor; magnetic field sensor;coolant thermometer; oil pressure sensor; oil level sensor; air flowmeter; voltmeter; ammeter; humidity sensor; engine knock sensor; oilturbidity sensor; throttle position sensor; steering wheel torquesensor; wheel speed sensor; tachometer; speedometer; other velocitysensors; other position or displacement sensors; oxygen sensor; yaw,pitch and roll angular sensors; clock; odometer; power steering pressuresensor; pollution sensor; fuel gauge; cabin thermometer; transmissionfluid level sensor; gyroscopes or other angular rate sensors includingyaw, pitch and roll rate sensors; accelerometers including single axis,dual axis and triaxial accelerometers; an inertial measurement unit;coolant level sensor; transmission fluid turbidity sensor; brakepressure sensor; tire pressure sensor; tire temperature sensor, tireacceleration sensor; GPS receiver; DGPS receiver; and coolant pressuresensor.

The term “signal” as used herein generally refers to any time-varyingoutput from a component including electrical, acoustic, thermal,electromagnetic radiation or mechanical vibration.

Sensors on a vehicle are generally designed to measure particularparameters of particular vehicle components. However, frequently thesesensors also measure outputs from other vehicle components. For example,electronic airbag crash sensors currently in use contain one or moreaccelerometers for determining the accelerations of the vehiclestructure so that the associated electronic circuitry of the airbagcrash sensor can determine whether a vehicle is experiencing a crash ofsufficient magnitude so as to require deployment of the airbag. Eachaccelerometer continuously monitors the vibrations in the vehiclestructure regardless of the source of these vibrations. If a wheel isout of balance, or if there is extensive wear of the parts of the frontwheel mounting assembly, or wear in the shock absorbers, the resultingabnormal vibrations or accelerations can, in many cases, be sensed by acrash sensor accelerometer. There are other cases, however, where thesensitivity or location of an airbag crash sensor accelerometer is notappropriate and one or more additional accelerometers or gyroscopes maybe mounted onto a vehicle for the purposes of this invention. Someairbag crash sensors are not sufficiently sensitive accelerometers orhave sufficient dynamic range for the purposes herein.

For example, a technique for some implementations of an inventiondisclosed herein is the use of multiple accelerometers and/ormicrophones that will allow the system to locate the source of anymeasured vibrations based on the time of flight, time of arrival,direction of arrival and/or triangulation techniques. Once a distributedaccelerometer installation, or one or more IMUs, has been implemented topermit this source location, the same sensors can be used for smartercrash sensing as it can permit the determination of the location of theimpact on the vehicle. Once the impact location is known, a highlytailored algorithm can be used to accurately forecast the crash severitymaking use of knowledge of the force vs. crush properties of the vehicleat the impact location.

Every component of a vehicle can emit various signals during its life.These signals can take the form of electromagnetic radiation, acousticradiation, thermal radiation, vibrations transmitted through the vehiclestructure and voltage or current fluctuations, depending on theparticular component. When a component is functioning normally, it maynot emit a perceptible signal. In that case, the normal signal is nosignal, i.e., the absence of a signal. In most cases, a component willemit signals that change over its life and it is these changes whichtypically contain information as to the state of the component, e.g.,whether failure of the component is impending. Usually components do notfail without warning. However, most such warnings are either notperceived or if perceived, are not understood by the vehicle operatoruntil the component actually fails and, in some cases, a breakdown ofthe vehicle occurs.

An important system and method as disclosed herein for acquiring datafor performing the diagnostics, prognostics and health monitoringfunctions makes use of the acoustic transmissions from variouscomponents. This can involve the placement of one or more microphones,accelerometers, or other vibration sensors onto and/or at a variety oflocations within the vehicle where the sound or vibrations are mosteffectively sensed. In addition to acquiring data relative to aparticular component, the same sensors can also obtain data that permitsanalysis of the vehicle environment. A pothole, for example, can besensed and located for possible notification to a road authority if alocation determining apparatus is also resident on the vehicle.

In a few years, it is expected that various roadways will have systemsfor automatically guiding vehicles operating thereon. Such systems havebeen called “smart highways” and are part of the field of intelligenttransportation systems (ITS). If a vehicle operating on such a smarthighway were to breakdown due to the failure of a component, seriousdisruption of the system could result and the safety of other users ofthe smart highway could be endangered.

When a vehicle component begins to change its operating behavior, it isnot always apparent from the particular sensors which are monitoringthat component, if any. The output from any one of these sensors can benormal even though the component is failing. By analyzing the output ofa variety of sensors, however, the pending failure can frequently bediagnosed. For example, the rate of temperature rise in the vehiclecoolant, if it were monitored, might appear normal unless it were knownthat the vehicle was idling and not traveling down a highway at a highspeed. Even the level of coolant temperature which is in the normalrange could be in fact abnormal in some situations signifying a failingcoolant pump, for example, but not detectable from the coolantthermometer alone.

The pending failure of some components is difficult to diagnose andsometimes the design of the component requires modification so that thediagnosis can be more readily made. A fan belt, for example, frequentlybegins failing as a result of a crack of the inner surface. The belt canbe designed to provide a sonic or electrical signal when this crackingbegins in a variety of ways. Similarly, coolant hoses can be designedwith an intentional weak spot where failure will occur first in acontrolled manner that can also cause a whistle sound as a small amountof steam exits from the hose. This whistle sound can then be sensed by ageneral purpose microphone, for example.

In FIG. 1, a generalized component 35 emitting several signals which aretransmitted along a variety of paths, sensed by a variety of sensors andanalyzed by the diagnostic device in accordance with the invention isillustrated schematically. Component 35 is mounted to a vehicle 52 andduring operation it emits a variety of signals such as acoustic 36,electromagnetic radiation 37, thermal radiation 38, current and voltagefluctuations in conductor 39 and mechanical vibrations 40. Varioussensors are mounted in the vehicle to detect the signals emitted by thecomponent 35. These include one or more vibration sensors(accelerometers) 44, 46 and/or gyroscopes or one or more IMUs, one ormore acoustic sensors 41, 47, electromagnetic radiation sensors 42, heatradiation sensors 43 and voltage or current sensors 45.

In addition, various other sensors 48, 49 measure other parameters ofother components that in some manner provide information directly orindirectly on the operation of component 35. Each of the sensorsillustrated in FIG. 1 can be connected to a data bus 50. A diagnosticmodule 51, in accordance with the invention, can also be attached to thevehicle data bus 50 and it can receive the signals generated by thevarious sensors. The sensors may however be wirelessly connected to thediagnostic module 51 and be integrated into a wireless power andcommunications system or a combination of wired and wirelessconnections. The wireless connection of one or more sensors to areceiver, controller or diagnostic module is an important teaching ofone or more of the inventions disclosed herein.

The diagnostic module 51 will analyze the received data in light of thedata values or patterns itself either statically or over time. In somecases, a pattern recognition algorithm as discussed below will be usedand in others, a deterministic algorithm may also be used either aloneor in combination with the pattern recognition algorithm. Additionally,when a new data value or sequence is discovered the information can besent to an off-vehicle location, perhaps a dealer or manufacturer site,and a search can be made for other similar cases and the resultsreported back to the vehicle. Also additionally as more and morevehicles are reporting cases that perhaps are also examined by engineersor mechanics, the results can be sent to the subject vehicle or to allsimilar vehicles and the diagnostic software updated automatically.Thus, all vehicles can have the benefit from information relative toperforming the diagnostic function. Similarly, the vehicle dealers andmanufacturers can also have up-to-date information as to how aparticular class or model of vehicle is performing. This telematicsfunction is discussed in more detail elsewhere herein. By means of thissystem, a vehicle diagnostic system can predict component failures longbefore they occur and thus prevent on-road problems.

An important function that can be performed by the diagnostic systemherein is to substantially diagnose the vehicle's own problems ratherthen, as is the case with the prior art, forwarding raw data to acentral site for diagnosis. Eventually, a prediction as to the failurepoint of all significant components can be made and the owner can have aprediction that the fan belt will last another 20,000 miles, or that thetires should be rotated in 2,000 miles or replaced in 20,000 miles. Thisinformation can be displayed or reported orally or sent to the dealerwho can then schedule a time for the customer to visit the dealership orfor the dealer to visit the vehicle wherever it is located. If it isdisplayed, it can be automatically displayed periodically or when thereis urgency or whenever the operator desires. The display can be locatedat any convenient place such as the dashboard or it can be a heads-updisplay. The display can be any convenient technology such as an LCDdisplay or an OLED based display. This can permit the vehiclemanufacturer to guarantee that the owner will never experience a vehiclebreakdown provided he or she permits the dealer to service the vehicleat appropriate times based on the output of the prognostics system.

It is worth emphasizing that in many cases, it is the rate that aparameter is changing that can be as or more important than the actualvalue in predicting when a component is likely to fail. In a simple casewhen a tire is losing pressure, for example, it is a quite differentsituation if it is losing one psi per day or one psi per minute.Similarly for the tire case, if the tire is heating up at one degree perhour or 100 degrees per hour may be more important in predicting failuredue to delamination or overloading than the particular temperature ofthe tire.

The diagnostic module, or other component, can also consider situationawareness factors such as the age or driving habits of the operator, thelocation of the vehicle (e.g., is it in the desert, in the arctic inwinter), the season, the weather forecast, the length of a proposedtrip, the number and location of occupants of the vehicle etc. Thesystem may even put limits on the operation of the vehicle such asturning off unnecessary power consuming components if the alternator isfailing or limiting the speed of the vehicle if the driver is an elderlywoman sitting close to the steering wheel, for example. Furthermore, thesystem may change the operational parameters of the vehicle such as theengine RPM or the fuel mixture if doing so will prolong vehicleoperation. In some cases where there is doubt whether a component isfailing, the vehicle operating parameters may be temporarily varied bythe system in order to accentuate the signal from the component topermit more accurate diagnosis.

In addition to the above discussion there are some diagnostic featuresalready available on some vehicles some of which are related to thefederally mandated OBD-II and can be included in the general diagnosticsand health monitoring features of this invention. In typicalapplications, the set of diagnostic data includes at least one of thefollowing: diagnostic trouble codes, vehicle speed, fuel level, fuelpressure, miles per gallon, engine RPM, mileage, oil pressure, oiltemperature, tire pressure, tire temperature, engine coolanttemperature, intake-manifold pressure, engine-performance tuningparameters, alarm status, accelerometer status, cruise-control status,fuel-injector performance, spark-plug timing, and a status of ananti-lock braking system.

The data parameters within the set describe a variety of electrical,mechanical, and emissions-related functions in the vehicle. Several ofthe more significant parameters from the set are:

Pending DTCs (Diagnostic Trouble Codes)

Ignition Timing Advance

Calculated Load Value

Air Flow Rate MAF Sensor

Engine RPM

Engine Coolant Temperature

Intake Air Temperature

Absolute Throttle Position Sensor

Vehicle Speed

Short-Term Fuel Trim

Long-Term Fuel Trim

MIL Light Status

Oxygen Sensor Voltage

Oxygen Sensor Location

Delta Pressure Feedback EGR Pressure Sensor

Evaporative Purge Solenoid Duty cycle

Fuel Level Input Sensor

Fuel Tank Pressure Voltage

Engine Load at the Time of Misfire

Engine RPM at the Time of Misfire

Throttle Position at the Time of Misfire

Vehicle Speed at the Time of Misfire

Number of Misfires

Transmission Fluid Temperature

PRNDL position (1,2,3,4,5=neutral, 6=reverse)

Number of Completed OBDII Trips, and

Battery Voltage.

When the diagnostic system determines that the operator is operating thevehicle in such a manner that the failure of a component is accelerated,then a warning can be issued to the operator. For example, the drivermay have inadvertently placed the automatic gear shift lever in a lowergear and be driving at a higher speed than he or she should for thatgear. In such a case, the driver can be notified to change gears.

Managing the diagnostics and prognostics of a complex system has beentermed “System Health Management” and has not been applied to over theroad vehicles such as trucks and automobiles. Such systems are used forfault detection and identification, failure prediction (estimating thetime to failure), tracking degradation, maintenance scheduling, errorcorrection in the various measurements which have been corrupted andthese same tasks are applicable here.

Various sensors, both wired and wireless, will be discussed below.Representative of such sensors are those available from Honeywell whichare MEMS-based sensors for measuring temperature, pressure, acousticemission, strain, and acceleration. The devices are based on resonantmicrobeam force sensing technology. Coupled with a precision siliconmicrostructure, the resonant microbeams provide a high sensitivity formeasuring inertial acceleration, inclination, and vibrations. Alternatedesigns based on SAW technology lend themselves more readily to wirelessand powerless operation as discussed below. The Honeywell sensors can benetworked wirelessly but still require power.

Since this system is independent of the dedicated sensor monitoringsystem and instead is observing more than one sensor, inconsistencies insensor output can be detected and reported indicating the possibleerratic or inaccurate operation of a sensor even if this is intermittent(such as may be caused by a lose wire) thus essentially eliminating manyof the problems reported in the above-referenced article “What's Buggingthe High-Tech Car”. Furthermore, the software can be independent of thevehicle specific software for a particular sensor and system and canfurther be based on pattern recognition, to be discussed next, renderingit even less likely to provide the wrong diagnostic. Since the outputfrom the diagnostic and prognostic system herein described can be sentvia telematics to the dealer and vehicle manufacturer, the occurrence ofa sensor or system failure can be immediately logged to form a frequencyof failure log for a particular new vehicle model allowing themanufacturer to more quickly schedule a recall if a previously unknownproblem surfaces in the field.

1.2 Pattern Recognition

In accordance with at least one invention, each of the signals emittedby the sensors can be converted into electrical signals and thendigitized (i.e., the analog signal is converted into a digital signal)to create numerical time series data which is entered into a processor.Pattern recognition algorithms can be applied by the processor toattempt to identify and classify patterns in this time series data. Fora particular component, such as a tire for example, the algorithmattempts to determine from the relevant digital data whether the tire isfunctioning properly or whether it requires balancing, additional air,or perhaps replacement.

Frequently, the data entered into the pattern recognition algorithmneeds to be preprocessed before being analyzed. The data from a wheelspeed sensor, for example, might be used “as is” for determining whethera particular tire is operating abnormally in the event it is unbalanced,whereas the integral of the wheel speed data over a long time period (apreprocessing step), when compared to such sensors on different wheels,might be more useful in determining whether a particular tire is goingflat and therefore needs air. This is the basis of some tire monitorsnow on the market. Such indirect systems are not permitted as a meansfor satisfying federal safety requirements. These systems generallydepend on the comparison of the integral of the wheel speed to determinethe distance traveled by the wheel surface and that system is thencompared with other wheels on the vehicle to determine that one tire hasrelatively less air than another. Of course this system fails if all ofthe tires have low pressure. One solution is to compare the distancetraveled by a wheel with the distance that it should have traveled. Ifthe angular motion (displacement and/or velocity) of the wheel axle isknown, than this comparison can be made directly. Alternately, if theposition of the vehicle is accurately monitored so that the actualtravel along its path can be determined through a combination of GPS andan IMU, for example, then again the pressure within a vehicle tire canbe determined.

In some cases, the frequencies present in a set of data are a betterpredictor of component failures than the data itself. For example, whena motor begins to fail due to worn bearings, certain characteristicfrequencies began to appear. In most cases, the vibrations arising fromrotating components, such as the engine, will be normalized based on therotational frequency. Moreover, the identification of which component iscausing vibrations present in the vehicle structure can frequently beaccomplished through a frequency analysis of the data. For these cases,a Fourier transformation of the data can be made prior to entry of thedata into a pattern recognition algorithm. Wavelet transforms and othermathematical transformations are also made for particular patternrecognition purposes in practicing the teachings of this invention. Someof these include shifting and combining data to determine phase changesfor example, differentiating the data, filtering the data and samplingthe data. Also, there exist certain more sophisticated mathematicaloperations that attempt to extract or highlight specific features of thedata. The inventions herein contemplate the use of a variety of thesepreprocessing techniques and the choice of which one or ones to use isleft to the skill of the practitioner designing a particular diagnosticand prognostic module. Note, whenever diagnostics is used below it willbe assumed to also include prognostics.

As shown in FIG. 1, the diagnostic module 51 has access to the outputdata of each of the sensors that are known to have or potentially mayhave information relative to or concerning the component 35. This dataappears as a series of numerical values each corresponding to a measuredvalue at a specific point in time. The cumulative data from a particularsensor is called a time series of individual data points. The diagnosticmodule 51 compares the patterns of data received from each sensorindividually, or in combination with data from other sensors, withpatterns for which the diagnostic module has been programmed or trainedto determine whether the component is functioning normally orabnormally.

Important to some embodiments of the inventions herein is the manner inwhich the diagnostic module 51 determines a normal pattern from anabnormal pattern and the manner in which it decides what data to usefrom the vast amount of data available. This can be accomplished usingpattern recognition technologies such as artificial neural networks andtraining and in particular, combination neural networks as described inU.S. patent application Ser. No. 10/413,426 (Publication 20030209893).The theory of neural networks including many examples can be found inseveral books on the subject including: (1) Techniques And ApplicationOf Neural Networks, edited by Taylor, M. and Lisboa, P., Ellis Horwood,West Sussex, England, 1993; (2) Naturally Intelligent Systems, byCaudill, M. and Butler, C., MIT Press, Cambridge Mass., 1990; (3) J. M.Zaruda, Introduction to Artificial Neural Systems, West Publishing Co.,N.Y., 1992, (4) Digital Neural Networks, by Kung, S. Y., PTR PrenticeHall, Englewood Cliffs, N.J., 1993, Eberhart, R., Simpson, P., (5)Dobbins, R., Computational Intelligence PC Tools, Academic Press, Inc.,1996, Orlando, Fla., (6) Cristianini, N. and Shawe-Taylor, J. AnIntroduction to Support Vector Machines and other kernal-based learningmethods, Cambridge University Press, Cambridge England, 2000; (7)Proceedings of the 2000 6^(th) IEEE International Workshop on CellularNeural Networks and their Applications (CNNA 2000), IEEE, PiscatawayN.J.; and (8) Sinha, N. K. and Gupta, M. M. Soft Computing & IntelligentSystems, Academic Press 2000 San Diego, Calif. The neural networkpattern recognition technology is one of the most developed of patternrecognition technologies. The invention described herein frequently usescombinations of neural networks to improve the pattern recognitionprocess, as discussed in detail in U.S. patent application Ser. No.10/413,426.

The neural network pattern recognition technology is one of the mostdeveloped of pattern recognition technologies. The neural network willbe used here to illustrate one example of a pattern recognitiontechnology but it is emphasized that this invention is not limited toneural networks. Rather, the invention may apply any known patternrecognition technology including various segmentation techniques, sensorfusion and various correlation technologies. In some cases, the patternrecognition algorithm is generated by an algorithm-generating programand in other cases, it is created by, e.g., an engineer, scientist orprogrammer. A brief description of a particular simple example of aneural network pattern recognition technology is set forth below.

Neural networks are constructed of processing elements known as neuronsthat are interconnected using information channels called interconnectsand are arranged in a plurality of layers. Each neuron can have multipleinputs but generally only one output. Each output however is usuallyconnected to many, frequently all, other neurons in the next layer. Theneurons in the first layer operate collectively on the input data asdescribed in more detail below. Neural networks learn by extractingrelational information from the data and the desired output. Neuralnetworks have been applied to a wide variety of pattern recognitionproblems including automobile occupant sensing, speech recognition,optical character recognition and handwriting analysis.

To train a neural network, data is provided in the form of one or moretime series that represents the condition to be diagnosed, which can beinduced to artificially create an abnormally operating component, aswell as normal operation. In the training stage of the neural network orother type of pattern recognition algorithm, the time series data forboth normal and abnormal component operation is entered into a processorwhich applies a neural network-generating program to output a neuralnetwork capable of determining abnormal operation of a component.

As an example, the simple case of an out-of-balance tire will be used.Various sensors on the vehicle can be used to extract information fromsignals emitted by the tire such as an accelerometer, a torque sensor onthe steering wheel, the pressure output of the power steering system, atire pressure monitor or tire temperature monitor. Other sensors thatmight not have an obvious relationship to tire unbalance (or imbalance)are also included such as, for example, the vehicle speed or wheel speedthat can be determined from the anti-lock brake (ABS) system. Data istaken from a variety of vehicles where the tires were accuratelybalanced under a variety of operating conditions also for cases wherevarying amounts of tire unbalance was intentionally introduced. Once thedata had been collected, some degree of pre-processing (e.g., time orfrequency modification) and/or feature extraction is usually performedto reduce the total amount of data fed to the neural network-generatingprogram. In the case of the unbalanced tire, the time period betweendata points might be selected such that there are at least ten datapoints per revolution of the wheel. For some other application, the timeperiod might be one minute or one millisecond.

Once the data has been collected, it is processed by the neuralnetwork-generating program, for example, if a neural network patternrecognition system is to be used. Such programs are availablecommercially, e.g., from NeuralWare of Pittsburgh, Pa. or fromInternational Scientific Research, Inc., of Panama for modular neuralnetworks. The program proceeds in a trial and error manner until itsuccessfully associates the various patterns representative of abnormalbehavior, an unbalanced tire in this case, with that condition. Theresulting neural network can be tested to determine if some of the inputdata from some of the sensors, for example, can be eliminated. In thismanner, the engineer can determine what sensor data is relevant to aparticular diagnostic problem. The program then generates an algorithmthat is programmed onto a microprocessor, microcontroller, neuralprocessor, FPGA, or DSP (herein collectively referred to as amicroprocessor or processor). Such a microprocessor appears inside thediagnostic module 51 in FIG. 1.

Once trained, the neural network, as represented by the algorithm, isinstalled in a processor unit of a motor vehicle and will now recognizean unbalanced tire on the vehicle when this event occurs. At that time,when the tire is unbalanced, the diagnostic module 51 will receiveoutput from the sensors, determine whether the output is indicative ofabnormal operation of the tire, e.g., lack of tire balance, and instructor direct another vehicular system to respond to the unbalanced tiresituation. Such an instruction may be a message to the driver indicatingthat the tire should now be balanced, as described in more detail below.The message to the driver is provided by an output device coupled to orincorporated within the module 51, e.g., an icon or text display, andmay be a light on the dashboard, a vocal tone or any other recognizableindication apparatus. A similar message may also be sent to the dealer,vehicle manufacturer or other repair facility or remote facility via acommunications channel between the vehicle and the dealer or repairfacility which is established by a suitable transmission device.

It is important to note that there may be many neural networks involvedin a total vehicle diagnostic system. These can be organized either inparallel, series, as an ensemble, cellular neural network or as amodular neural network system. In one implementation of a modular neuralnetwork, a primary neural network identifies that there is anabnormality and tries to identify the likely source. Once a choice hasbeen made as to the likely source of the abnormality, another, specificneural network of a group of neural networks can be called upon todetermine the exact cause of the abnormality. In this manner, the neuralnetworks are arranged in a tree pattern with each neural network trainedto perform a particular pattern recognition task.

Discussions on the operation of a neural network can be found in theabove references on the subject and are understood by those skilled inthe art. Neural networks are the most well-known of the patternrecognition technologies based on training, although neural networkshave only recently received widespread attention and have been appliedto only very limited and specialized problems in motor vehicles such asoccupant sensing (by the current assignee) and engine control (by FordMotor Company). Other non-training based pattern recognitiontechnologies exist, such as fuzzy logic. However, the programmingrequired to use fuzzy logic, where the patterns must be determine by theprogrammer, usually render these systems impractical for general vehiclediagnostic problems such as described herein (although their use is notimpossible in accordance with the teachings of the invention).Therefore, preferably the pattern recognition systems that learn bytraining are used herein. It should be noted that neural networks arefrequently combined with fuzzy logic and such a combination iscontemplated herein. The neural network is the first highly successfulof what will be a variety of pattern recognition techniques based ontraining. There is nothing that suggests that it is the only or even thebest technology. The characteristics of all of these technologies whichrender them applicable to this general diagnostic problem include theuse of time-of frequency-based input data and that they are trainable.In most cases, the pattern recognition technology learns from examplesof data characteristic of normal and abnormal component operation.

A diagram of one example of a neural network used for diagnosing anunbalanced tire, for example, based on the teachings of this inventionis shown in FIG. 2. The process can be programmed to periodically testfor an unbalanced tire. Since this need be done only infrequently, thesame processor can be used for many such diagnostic problems. When theparticular diagnostic test is run, data from the previously determinedrelevant sensor(s) is preprocessed and analyzed with the neural networkalgorithm. For the unbalanced tire, using the data from an accelerometerfor example, the digital acceleration values from the analog-to-digitalconverter in the accelerometer are entered into nodes 1 through n andthe neural network algorithm compares the pattern of values on nodes 1through n with patterns for which it has been trained as follows.

Each of the input nodes is usually connected to each of the second layernodes, h-1, h-2, . . . , h-n, called the hidden layer, eitherelectrically as in the case of a neural computer, or throughmathematical functions containing multiplying coefficients calledweights, in the manner described in more detail in the above references.At each hidden layer node, a summation occurs of the values from each ofthe input layer nodes, which have been operated on by functionscontaining the weights, to create a node value. Similarly, the hiddenlayer nodes are, in a like manner, connected to the output layernode(s), which in this example is only a single node 0 representing thedecision to notify the driver, and/or a remote facility, of theunbalanced tire. During the training phase, an output node value of 1,for example, is assigned to indicate that the driver should be notifiedand a value of 0 is assigned to not notifying the driver. Once again,the details of this process are described in above-referenced texts andwill not be presented in detail here.

In the example above, twenty input nodes were used, five hidden layernodes and one output layer node. In this example, only one sensor wasconsidered and accelerations from only one direction were used. If otherdata from other sensors such as accelerations from the vertical orlateral directions were also used, then the number of input layer nodeswould increase. Again, the theory for determining the complexity of aneural network for a particular application has been the subject of manytechnical papers and will not be presented in detail here. Determiningthe requisite complexity for the example presented here can beaccomplished by those skilled in the art of neural network design. Alsoone particular preferred type of neural network has been discussed. Manyother types exist as discussed in the above references and theinventions herein is not limited to the particular type discussed here.

Briefly, the neural network described above defines a method, using apattern recognition system, of sensing an unbalanced tire anddetermining whether to notify the driver, and/or a remote facility, andcomprises the steps of:

(a) obtaining an acceleration signal from an accelerometer mounted on avehicle;

(b) converting the acceleration signal into a digital time series;

(c) entering the digital time series data into the input nodes of theneural network;

(d) performing a mathematical operation on the data from each of theinput nodes and inputting the operated on data into a second series ofnodes wherein the operation performed on each of the input node dataprior to inputting the operated-on value to a second series node isdifferent from that operation performed on some other input node data(e.g., a different weight value can be used);

(e) combining the operated-on data from most or all of the input nodesinto each second series node to form a value at each second series node;

(f) performing a mathematical operation on each of the values on thesecond series of nodes and inputting this operated-on data into anoutput series of nodes wherein the operation performed on each of thesecond series node data prior to inputting the operated-on value to anoutput series node is different from that operation performed on someother second series node data;

(g) combining the operated-on data from most or all of the second seriesnodes into each output series node to form a value at each output seriesnode; and,

(h) notifying a driver if the value on one output series node is withina selected range signifying that a tire requires balancing.

This method can be generalized to a method of predicting that acomponent of a vehicle will fail comprising the steps of:

(a) sensing a signal emitted from the component;

(b) converting the sensed signal into a digital time series;

(c) entering the digital time series data into a pattern recognitionalgorithm;

(d) executing the pattern recognition algorithm to determine if thereexists within the digital time series data a pattern characteristic ofabnormal operation of the component; and

(e) notifying a driver and/or a remote facility if the abnormal patternis recognized.

The particular neural network described and illustrated above contains asingle series of hidden layer nodes. In some network designs, more thanone hidden layer is used, although only rarely will more than two suchlayers appear. There are of course many other variations of the neuralnetwork architecture illustrated above which appear in the referencedliterature. For the purposes herein, therefore, “neural network” can bedefined as a system wherein the data to be processed is separated intodiscrete values which are then operated on and combined in at least atwo stage process and where the operation performed on the data at eachstage is in general different for each discrete value and where theoperation performed is at least determined through a training process. Adifferent operation here is meant any difference in the way that theoutput of a neuron is treated before it is inputted into another neuronsuch as multiplying it by a different weight or constant.

The implementation of neural networks can take on at least two forms, analgorithm programmed on a digital microprocessor, FPGA, DSP or in aneural computer (including a cellular neural network or support vectormachine). In this regard, it is noted that neural computer chips are nowbecoming available.

In the example above, only a single component failure was discussedusing only a single sensor since the data from the single sensorcontains a pattern which the neural network was trained to recognize aseither normal operation of the component or abnormal operation of thecomponent. The diagnostic module 51 contains preprocessing and neuralnetwork algorithms for a number of component failures. The neuralnetwork algorithms are generally relatively simple, requiring only arelatively small number of lines of computer code. A single generalneural network program can be used for multiple pattern recognitioncases by specifying different coefficients for the various node inputs,one set for each application. Thus, adding different diagnostic checkshas only a small affect on the cost of the system. Also, the system canhave available to it all of the information available on the data bus.

During the training process, the pattern recognition program sorts outfrom the available vehicle data on the data bus or from other sources,those patterns that predict failure of a particular component. If morethan one sensor is used to sense the output from a component, such astwo spaced-apart microphones or acceleration sensors, then the locationof the component can sometimes be determined by triangulation based onthe phase difference, time of arrival and/or angle of arrival of thesignals to the different sensors. In this manner, a particular vibratingtire can be identified, for example. Since each tire on a vehicle doesnot always make the same number of revolutions in a given time period, atire can be identified by comparing the wheel sensor output with thevibration or other signal from the tire to identify the failing tire.The phase of the failing tire will change relative to the other tires,for example. This technique can also be used to associate a tirepressure monitor RF signal with a particular tire. An alternate methodfor tire identification makes use of an RFID tag or an RFID switch asdiscussed below.

In view of the foregoing, a method for diagnosing whether one or morecomponents of a vehicle are operating abnormally would entail in atraining stage, obtaining output from the sensors during normaloperation of the components, adjusting each component to induce abnormaloperation thereof and obtaining output from the sensors during theinduced abnormal operation, and

determining which sensors provide data about abnormal operation of eachcomponent based on analysis of the output from the sensors during normaloperation and during induced abnormal operation of the component, e.g.,differences between signals output from the sensors during normal andabnormal operation. The output from the sensors can be processed andpre-processed as described above. When obtaining output from the sensorsduring abnormal component operation, different abnormalities can beinduced in the components, one abnormality in one component at each timeand/or multiple abnormalities in multiple components at one time.

During operation of the vehicle, output from the sensors is received anda determination is made whether any of the components are operatingabnormally by analyzing the output from those sensors which have beendetermined to provide data about abnormal operation of that component.This determination is used to alert a driver of the vehicle, a vehiclemanufacturer, a vehicle dealer or a vehicle repair facility about theabnormal operation of a component. As mentioned above, the determinationof whether any of the components are operating abnormally may involveconsidering output from only those sensors which have been determined toprovide data about abnormal operation of that component. This could be asubset of the sensors, although it is possible when using a neuralnetwork to input all of the sensor data with the neural network beingdesigned to disregard output from sensors which have no bearing on thedetermination of abnormal operation of the component operatingabnormally.

When a combination neural network 810 is used, its training can involvemultiple steps. With reference to FIG. 92, after data acquisition fromthe sensors 811, a first neural network 812 could be designed todetermine whether the data from the sensors being input thereincorresponds to data obtained during normal operation of the components.If so, the output from this first neural network 812 would be anindication of normal vehicular operation (possibly displayed to thedriver) and which would cause the system to obtain new data 811 at apreset time interval or upon occurrence of a condition. If not, theexistence of abnormal operation of at least one component is indicated(as well as a possible condition of entry of bad data). The combinationneural network 810 includes a second neural network 813 which receivesthe data and is trained to output an indication of which component isoperating abnormally and possibly the exact manner in which thecomponent is operating abnormally, e.g., an unbalanced tire or anunderinflated tire. This output can be sent to the driver, a vehicledealer, manufacturer, repair facility, etc. 814 via a display device,transmission device and other notification, alert, alarm and/or warningsystems. After a preset time interval or upon occurrence of a condition,new data is acquired.

With reference to FIG. 93, a second combination neural network 815,after data acquisition from the sensors 816, a first neural network 817could be designed to determine whether the data from the sensors beinginput therein corresponds to data obtained during normal operation ofthe components. If so, the output from this first neural network 817would be an indication of normal vehicular operation (possibly displayedto the driver) and which would cause the system to obtain new data 816at a preset time interval or upon occurrence of a condition. If not, theexistence of abnormal operation of at least one component is indicated(as well as a possible condition of entry of bad data). The combinationneural network 815 includes a second neural network 818 which receivesthe data and is trained to output an indication of which component isoperating abnormally. Depending on which component is determined to beoperating abnormally, data is provided to one of a plurality ofadditional neural networks 819, 820, 821, each of which is trained tooutput an indication of the specific manner of abnormal operation of aspecific component. Thus, neural network 819 is designed to be used onlywhen a problem with the tires of the vehicle is output from neuralnetwork 818, neural network 820 is designed to be used only when aproblem with the brakes of the vehicle is output from neural network818, and neural network 821 is designed to be used only when a problemwith the coolant system of the vehicle is output from neural network818. Only three neural networks 819, 820, 821 are shown, but there couldbe one trained for each component or set of like components.

Neural networks 819, 820, 821 can be provided with only a subset of thedata from all of the sensors, namely, data only from those sensorsdetermined in the training stage to have an effect on the determinationof the problem with the particular component the neural network isdiagnosing a problem with.

The output of the specific problem from one of neural networks 819, 820,821 is sent to the driver, a vehicle dealer, manufacturer, repairfacility, etc. 822 via a display device, transmission device and othernotification, alert, alarm and/or warning systems. After a preset timeinterval or upon occurrence of a condition, new data is acquired.

To preclude the bad data situation, an additional neural network can beused in either combination neural network 810 or 815 to process the dataand ascertain whether it is good or bad before providing the data to theneural network which determines abnormal operation of a component. InFIG. 3, a schematic of a vehicle with several components and severalsensors is shown in their approximate locations on a vehicle along witha total vehicle diagnostic system in accordance with the inventionutilizing a diagnostic module in accordance with the invention. A flowdiagram of information passing from the various sensors shown in FIG. 3onto the vehicle data bus, wireless communication system, wire harnessor a combination thereof, and thereby into the diagnostic device inaccordance with the invention is shown in FIG. 4 along with outputs to adisplay for notifying the driver and to the vehicle cellular phone, orother communication device, for notifying the dealer, vehiclemanufacturer or other entity concerned with the failure of a componentin the vehicle. If the vehicle is operating on a smart highway, forexample, the pending component failure information may also becommunicated to a highway control system and/or to other vehicles in thevicinity so that an orderly exiting of the vehicle from the smarthighway can be facilitated. FIG. 4 also contains the names of thesensors shown numbered in FIG. 3.

Note, where applicable in one or more of the inventions disclosedherein, any form of wireless communication is contemplated for intravehicle communications between various sensors and components includingamplitude modulation, frequency modulation, TDMA, CDMA, spread spectrum,ultra wideband and all variations. Similarly, all such methods are alsocontemplated for vehicle-to-vehicle or vehicle-to-infrastructurecommunication.

Sensor 1 is a crash sensor having an accelerometer (alternately one ormore dedicated accelerometers or IMUs 31 can be used), sensor 2 isrepresents one or more microphones, sensor 3 is a coolant thermometer,sensor 4 is an oil pressure sensor, sensor 5 is an oil level sensor,sensor 6 is an air flow meter, sensor 7 is a voltmeter, sensor 8 is anammeter, sensor 9 is a humidity sensor, sensor 10 is an engine knocksensor, sensor 11 is an oil turbidity sensor, sensor 12 is a throttleposition sensor, sensor 13 is a steering torque sensor, sensor 14 is awheel speed sensor, sensor 15 is a tachometer, sensor 16 is aspeedometer, sensor 17 is an oxygen sensor, sensor 18 is a pitch/rollsensor, sensor 19 is a clock, sensor 20 is an odometer, sensor 21 is apower steering pressure sensor, sensor 22 is a pollution sensor, sensor23 is a fuel gauge, sensor 24 is a cabin thermometer, sensor 25 is atransmission fluid level sensor, sensor 26 is a yaw sensor, sensor 27 isa coolant level sensor, sensor 28 is a transmission fluid turbiditysensor, sensor 29 is brake pressure sensor and sensor 30 is a coolantpressure sensor. Other possible sensors include a temperaturetransducer, a pressure transducer, a liquid level sensor, a flow meter,a position sensor, a velocity sensor, a RPM sensor, a chemical sensorand an angle sensor, angular rate sensor or gyroscope.

If a distributed group of acceleration sensors or accelerometers areused to permit a determination of the location of a vibration source,the same group can, in some cases, also be used to measure the pitch,yaw and/or roll of the vehicle eliminating the need for dedicatedangular rate sensors. In addition, as mentioned above, such a suite ofsensors can also be used to determine the location and severity of avehicle crash and additionally to determine that the vehicle is on theverge of rolling over. Thus, the same suite of accelerometers optimallyperforms a variety of functions including inertial navigation, crashsensing, vehicle diagnostics, roll-over sensing etc.

Consider now some examples. The following is a partial list of potentialcomponent failures and the sensors from the list in FIG. 4 that mightprovide information to predict the failure of the component:

Out of balance tires 1, 13, 14, 15, 20, 21 Front end out of alignment 1,13, 21, 26 Tune up required 1, 3, 10, 12, 15, 17, 20, 22 Oil changeneeded 3, 4, 5, 11 Motor failure 1, 2, 3, 4, 5, 6, 10, 12, 15, 17, 22Low tire pressure 1, 13, 14, 15, 20, 21 Front end looseness 1, 13, 16,21, 26 Cooling system failure 3, 15, 24, 27, 30 Alternator problems 1,2, 7, 8, 15, 19, 20 Transmission problems 1, 3, 12, 15, 16, 20, 25, 28Differential problems 1, 12, 14 Brakes 1, 2, 14, 18, 20, 26, 29Catalytic converter and muffler 1, 2, 12, 15, 22 Ignition 1, 2, 7, 8, 9,10, 12, 17, 23 Tire wear 1, 13, 14, 15, 18, 20, 21, 26 Fuel leakage 20,23 Fan belt slippage 1, 2, 3, 7, 8, 12, 15, 19, 20 Alternatordeterioration 1, 2, 7, 8, 15, 19 Coolant pump failure 1, 2, 3, 24, 27,30 Coolant hose failure 1, 2, 3, 27, 30 Starter failure 1, 2, 7, 8, 9,12, 15 Dirty air filter 2, 3, 6, 11, 12, 17, 22

Several interesting facts can be deduced from a review of the abovelist. First, all of the failure modes listed can be at least partiallysensed by multiple sensors. In many cases, some of the sensors merelyadd information to aid in the interpretation of signals received fromother sensors. In today's automobile, there are few if any cases wheremultiple sensors are used to diagnose or predict a problem. In fact,there is virtually no failure prediction (prognostics) undertaken atall. Second, many of the failure modes listed require information frommore than one sensor. Third, information for many of the failure modeslisted cannot be obtained by observing one data point in time as is nowdone by most vehicle sensors. Usually an analysis of the variation in aparameter as a function of time is necessary. In fact, the associationof data with time to create a temporal pattern for use in diagnosingcomponent failures in automobile is believed to be unique to theinventions herein as is the combination of several such temporalpatterns. Fourth, the vibration measuring capability of the airbag crashsensor, or other accelerometer or IMU, is useful for most of the casesdiscussed above yet there is no such current use of accelerometers. Theairbag crash sensor is used only to detect crashes of the vehicle.Fifth, the second most used sensor in the above list, a microphone, doesnot currently appear on any automobiles, yet sound is the signal mostoften used by vehicle operators and mechanics to diagnose vehicleproblems. Another sensor that is listed above which also does notcurrently appear on automobiles is a pollution sensor. This is typicallya chemical sensor mounted in the exhaust system for detecting emissionsfrom the vehicle. It is expected that this and other chemical andbiological sensors will be used more in the future. Such a sensor can beused to monitor the intake of air from outside the vehicle to permitsuch a flow to be cut off when it is polluted. Similarly, if theinterior air is polluted, the exchange with the outside air can beinitiated.

In addition, from the foregoing depiction of different sensors whichreceive signals from a plurality of components, it is possible for asingle sensor to receive and output signals from a plurality ofcomponents which are then analyzed by the processor to determine if anyone of the components for which the received signals were obtained bythat sensor is operating in an abnormal state. Likewise, it is alsopossible to provide for a plurality of sensors each receiving adifferent signal related to a specific component which are then analyzedby the processor to determine if that component is operating in anabnormal state. Neural networks can simultaneously analyze data frommultiple sensors of the same type or different types (a form of sensorfusion).

As can be appreciated from the above discussion, an invention describedherein brings several new improvements to vehicles including, but notlimited to, the use of pattern recognition technologies to diagnosepotential vehicle component failures, the use of trainable systemsthereby eliminating the need of complex and extensive programming, thesimultaneous use of multiple sensors to monitor a particular component,the use of a single sensor to monitor the operation of many vehiclecomponents, the monitoring of vehicle components which have no dedicatedsensors, and the notification of both the driver and possibly an outsideentity of a potential component failure prior to failure so that theexpected failure can be averted and vehicle breakdowns substantiallyeliminated. Additionally, improvements to the vehicle stability, crashavoidance, crash anticipation and occupant protection are available.

To implement a component diagnostic system for diagnosing the componentutilizing a plurality of sensors not directly associated with thecomponent, i.e., independent of the component, a series of tests areconducted. For each test, the signals received from the sensors areinput into a pattern recognition training algorithm with an indicationof whether the component is operating normally or abnormally (thecomponent being intentionally altered to provide for abnormaloperation). The data from the test are used to generate the patternrecognition algorithm, e.g., neural network, so that in use, the datafrom the sensors is input into the algorithm and the algorithm providesan indication of abnormal or normal operation of the component. Also, toprovide a more versatile diagnostic module for use in conjunction withdiagnosing abnormal operation of multiple components, tests may beconducted in which each component is operated abnormally while the othercomponents are operating normally, as well as tests in which two or morecomponents are operating abnormally. In this manner, the diagnosticmodule may be able to determine based on one set of signals from thesensors during use that either a single component or multiple componentsare operating abnormally. Additionally, if a failure occurs which wasnot forecasted, provision can be made to record the output of some orall of the vehicle data and later make it available to the vehiclemanufacturer for inclusion into the pattern recognition trainingdatabase. Also, it is not necessary that a neural network system that ison a vehicle be a static system and some amount of learning can, in somecases, be permitted. Additionally, as the vehicle manufacturer updatesthe neural networks, the newer version can be downloaded to particularvehicles either when the vehicle is at a dealership or wirelessly via acellular network or by satellite.

Furthermore, the pattern recognition algorithm may be trained based onpatterns within the signals from the sensors. Thus, by means of a singlesensor, it would be possible to determine whether one or more componentsare operating abnormally. To obtain such a pattern recognitionalgorithm, tests are conducted using a single sensor, such as amicrophone, and causing abnormal operation of one or more components,each component operating abnormally while the other components operatenormally and multiple components operating abnormally. In this manner,in use, the pattern recognition algorithm may analyze a signal from asingle sensor and determine abnormal operation of one or morecomponents. Note that in some cases, simulations can be used toanalytically generate the relevant data.

The discussion above has centered mainly on the blind training of apattern recognition system, such as a neural network, so that faults canbe discovered and failures forecast before they happen. Naturally, thediagnostic algorithms do not have to start out being totally dumb and infact, the physics or structure of the systems being monitored can beappropriately used to help structure or derive the diagnosticalgorithms. Such a system is described in a recent article “ImmobotsTake Control”, MIT Technology Review December, 2002. Also, of course, itis contemplated that once a potential failure has been diagnosed, thediagnostic system can in some cases act to change the operation ofvarious systems in the vehicle to prolong the time of a failingcomponent before the failure or in some rare cases, the situationcausing the failure might be corrected. An example of the first case iswhere the alternator is failing and various systems or components can beturned off to conserve battery power and an example of the second caseis rollover of a vehicle may be preventable through the properapplication of steering torque and wheel braking force. Such algorithmscan be based on pattern recognition or on models, as described in theImmobot article referenced above, or a combination thereof and all suchsystems are contemplated by the invention described herein.

1.3 SAW and Other Wireless Sensors

Many sensors are now in vehicles and many more will be installed invehicles. The following disclosure is primarily concerned with wirelesssensors which can be based on MEMS, SAW and/or RFID technologies.Vehicle sensors include tire pressure, temperature and accelerationmonitoring sensors; weight or load measuring sensors; switches; vehicletemperature, acceleration, angular position, angular rate, angularacceleration sensors; proximity; rollover; occupant presence; humidity;presence of fluids or gases; strain; road condition and friction,chemical sensors and other similar sensors providing information to avehicle system, vehicle operator or external site. The sensors canprovide information about the vehicle and/or its interior or exteriorenvironment, about individual components, systems, vehicle occupants,subsystems, and/or about the roadway, ambient atmosphere, travelconditions and external objects.

For wireless sensors, one or more interrogators can be used each havingone or more antennas that transmit energy at radio frequency, or otherelectromagnetic frequencies, to the sensors and receive modulatedfrequency signals from the sensors containing sensor and/oridentification information. One interrogator can be used for sensingmultiple switches or other devices. For example, an interrogator maytransmit a chirp form of energy at 905 MHz to 925 MHz to a variety ofsensors located within and/or in the vicinity of the vehicle. Thesesensors may be of the RFID electronic type and/or of the surfaceacoustic wave (SAW) type or a combination thereof. In the electronictype, information can be returned immediately to the interrogator in theform of a modulated backscatter RF signal. In the case of SAW devices,the information can be returned after a delay. RFID tags may alsoexhibit a delay due to the charging of the energy storage device.Naturally, one sensor can respond in both the electronic (either RFID orbackscatter) and SAW delayed modes.

When multiple sensors are interrogated using the same technology, thereturned signals from the various sensors can be time, code, space orfrequency multiplexed. For example, for the case of the SAW technology,each sensor can be provided with a different delay or a different code.Alternately, each sensor can be designed to respond only to a singlefrequency or several frequencies. The radio frequency can be amplitude,code or frequency modulated. Space multiplexing can be achieved throughthe use of two or more antennas and correlating the received signals toisolate signals based on direction.

In many cases, the sensors will respond with an identification signalfollowed by or preceded by information relating to the sensed value,state and/or property. In the case of a SAW-based or RFID-based switch,for example, the returned signal may indicate that the switch is eitheron or off or, in some cases, an intermediate state can be providedsignifying that a light should be dimmed, rather than or on or off, forexample. Alternately or additionally, an RFID based switch can beassociated with a sensor and turned on or off based on an identificationcode or a frequency sent from the interrogator permitting a particularsensor or class of sensors to be selected.

SAW devices have been used for sensing many parameters including devicesfor chemical and biological sensing and materials characterization inboth the gas and liquid phase. They also are used for measuringpressure, strain, temperature, acceleration, angular rate and otherphysical states of the environment.

Economies are achieved by using a single interrogator or even a smallnumber of interrogators to interrogate many types of devices. Forexample, a single interrogator may monitor tire pressure andtemperature, the weight of an occupying item of the seat, the positionof the seat and seatback, as well as a variety of switches controllingwindows, door locks, seat position, etc. in a vehicle. Such aninterrogator may use one or multiple antennas and when multiple antennasare used, may switch between the antennas depending on what is beingmonitored.

Similarly, the same or a different interrogator can be used to monitorvarious components of the vehicle's safety system including occupantposition sensors, vehicle acceleration sensors, vehicle angularposition, velocity and acceleration sensors, related to both frontal,side or rear impacts as well as rollover conditions. The interrogatorcould also be used in conjunction with other detection devices such asweight sensors, temperature sensors, accelerometers which are associatedwith various systems in the vehicle to enable such systems to becontrolled or affected based on the measured state.

Some specific examples of the use of interrogators and responsivedevices will now be described.

The antennas used for interrogating the vehicle tire pressuretransducers can be located outside of the vehicle passenger compartment.For many other transducers to be sensed the antennas can be located atvarious positions within passenger compartment. At least one inventionherein contemplates, therefore, a series of different antenna systems,which can be electronically switched by the interrogator circuitry.Alternately, in some cases, all of the antennas can be left connectedand total transmitted power increased.

There are several applications for weight or load measuring devices in avehicle including the vehicle suspension system and seat weight sensorsfor use with automobile safety systems. As described in U.S. Pat. No.4,096,740, U.S. Pat. No. 4,623,813, U.S. Pat. No. 5,585,571, U.S. Pat.No. 5,663,531, U.S. Pat. No. 5,821,425 and U.S. Pat. No. 5,910,647 andInternational Publication No. WO 00/65320(A1), SAW devices areappropriate candidates for such weight measurement systems, although insome cases RFID systems can also be used with an associated sensor suchas a strain gage. In this case, the surface acoustic wave on the lithiumniobate, or other piezoelectric material, is modified in delay time,resonant frequency, amplitude and/or phase based on strain of the memberupon which the SAW device is mounted. For example, the conventional boltthat is typically used to connect the passenger seat to the seatadjustment slide mechanism can be replaced with a stud which is threadedon both ends. A SAW or other strain device can be mounted to the centerunthreaded section of the stud and the stud can be attached to both theseat and the slide mechanism using appropriate threaded nuts. Based onthe particular geometry of the SAW device used, the stud can result inas little as a 3 mm upward displacement of the seat compared to a normalbolt mounting system. No wires are required to attach the SAW device tothe stud other than for an antenna.

In use, the interrogator transmits a radio frequency pulse at, forexample, 925 MHz that excites antenna on the SAW strain measuringsystem. After a delay caused by the time required for the wave to travelthe length of the SAW device, a modified wave is re-transmitted to theinterrogator providing an indication of the strain of the stud with theweight of an object occupying the seat corresponding to the strain. Fora seat that is normally bolted to the slide mechanism with four bolts,at least four SAW strain sensors could be used. Since the individual SAWdevices are very small, multiple devices can be placed on a stud toprovide multiple redundant measurements, or permit bending and twistingstrains to be determined, and/or to permit the stud to be arbitrarilylocated with at least one SAW device always within direct view of theinterrogator antenna. In some cases, the bolt or stud will be made onnon-conductive material to limit the blockage of the RF signal. In othercases, it will be insulated from the slide (mechanism) and used as anantenna.

If two longitudinally spaced apart antennas are used to receive the SAWor RFID transmissions from the seat weight sensors, one antenna in frontof the seat and the other behind the seat, then the position of the seatcan be determined eliminating the need for current seat positionsensors. A similar system can be used for other seat and seatbackposition measurements.

For strain gage weight sensing, the frequency of interrogation can beconsiderably higher than that of the tire monitor, for example. However,if the seat is unoccupied, then the frequency of interrogation can besubstantially reduced. For an occupied seat, information as to theidentity and/or category and position of an occupying item of the seatcan be obtained through the multiple weight sensors described. For thisreason, and due to the fact that during the pre-crash event, theposition of an occupying item of the seat may be changing rapidly,interrogations as frequently as once every 10 milliseconds or faster canbe desirable. This would also enable a distribution of the weight beingapplied to the seat to be obtained which provides an estimation of thecenter of pressure and thus the position of the object occupying theseat. Using pattern recognition technology, e.g., a trained neuralnetwork, sensor fusion, fuzzy logic, etc., an identification of theobject can be ascertained based on the determined weight and/ordetermined weight distribution.

There are many other methods by which SAW devices can be used todetermine the weight and/or weight distribution of an occupying itemother than the method described above and all such uses of SAW strainsensors for determining the weight and weight distribution of anoccupant are contemplated. For example, SAW devices with appropriatestraps can be used to measure the deflection of the seat cushion top orbottom caused by an occupying item, or if placed on the seat belts, theload on the belts can determined wirelessly and powerlessly. Geometriessimilar to those disclosed in U.S. Pat. No. 6,242,701 (which disclosesmultiple strain gage geometries) using SAW strain-measuring devices canalso be constructed, e.g., any of the multiple strain gage geometriesshown therein.

Generally there is an RFID implementation that corresponds to each SAWimplementation. Therefore, where SAW is used herein the equivalent RFIDdesign will also be meant where appropriate.

Although a preferred method for using the invention is to interrogateeach of the SAW devices using wireless mechanisms, in some cases, it maybe desirable to supply power to and/or obtain information from one ormore of the SAW devices using wires. As such, the wires would be anoptional feature.

One advantage of the weight sensors of this invention along with thegeometries disclosed in the '701 patent and herein below, is that inaddition to the axial stress in the seat support, the bending moments inthe structure can be readily determined. For example, if a seat issupported by four “legs”, it is possible to determine the state ofstress, assuming that axial twisting can be ignored, using four straingages on each leg support for a total of 16 such gages. If the seat issupported by three legs, then this can be reduced to 12 gages.Naturally, a three-legged support is preferable to four since with fourlegs, the seat support is over-determined which severely complicates thedetermination of the stress caused by an object on the seat. Even withthree supports, stresses can be introduced depending on the nature ofthe support at the seat rails or other floor-mounted supportingstructure. If simple supports are used that do not introduce bendingmoments into the structure, then the number of gages per seat can bereduced to three, provided a good model of the seat structure isavailable. Unfortunately, this is usually not the case and most seatshave four supports and the attachments to the vehicle not only introducebending moments into the structure but these moments vary from oneposition to another and with temperature. The SAW strain gages of thisinvention lend themselves to the placement of multiple gages onto eachsupport as needed to approximately determine the state of stress andthus the weight of the occupant depending on the particular vehicleapplication. Furthermore, the wireless nature of these gages greatlysimplifies the placement of such gages at those locations that are mostappropriate.

An additional point should be mentioned. In many cases, thedetermination of the weight of an occupant from the static strain gagereadings yields inaccurate results due to the indeterminate stress statein the support structure. However, the dynamic stresses to a first orderare independent of the residual stress state. Thus, the change in stressthat occurs as a vehicle travels down a roadway caused by dips in theroadway can provide an accurate measurement of the weight of an objectin a seat. This is especially true if an accelerometer is used tomeasure the vertical excitation provided to the seat.

Some vehicle models provide load leveling and ride control functionsthat depend on the magnitude and distribution of load carried by thevehicle suspension. Frequently, wire strain gage technology is used forthese functions. That is, the wire strain gages are used to sense theload and/or load distribution of the vehicle on the vehicle suspensionsystem. Such strain gages can be advantageously replaced with straingages based on SAW technology with the significant advantages in termsof cost, wireless monitoring, dynamic range, and signal level. Inaddition, SAW strain gage systems can be more accurate than wire straingage systems.

A strain detector in accordance with this invention can convertmechanical strain to variations in electrical signal frequency with alarge dynamic range and high accuracy even for very small displacements.The frequency variation is produced through use of a surface acousticwave (SAW) delay line as the frequency control element of an oscillator.A SAW delay line comprises a transducer deposited on a piezoelectricmaterial such as quartz or lithium niobate which is arranged so as to bedeformed by strain in the member which is to be monitored. Deformationof the piezoelectric substrate changes the frequency controlcharacteristics of the surface acoustic wave delay line, therebychanging the frequency of the oscillator. Consequently, the oscillatorfrequency change is a measure of the strain in the member beingmonitored and thus the weight applied to the seat. A SAW straintransducer can be more accurate than a conventional resistive straingage.

Other applications of weight measuring systems for an automobile includemeasuring the weight of the fuel tank or other containers of fluid todetermine the quantity of fluid contained therein as described in moredetail below.

One problem with SAW devices is that if they are designed to operate atthe GHz frequency, the feature sizes become exceeding small and thedevices are difficult to manufacture, although techniques are nowavailable for making SAW devices in the tens of GHz range. On the otherhand, if the frequencies are considerably lower, for example, in thetens of megahertz range, then the antenna sizes become excessive. It isalso more difficult to obtain antenna gain at the lower frequencies.This is also related to antenna size. One method of solving this problemis to transmit an interrogation signal in the high GHz range which ismodulated at the hundred MHz range. At the SAW transducer, thetransducer is tuned to the modulated frequency. Using a nonlinear devicesuch as a Shocky diode, the modified signal can be mixed with theincoming high frequency signal and re-transmitted through the sameantenna. For this case, the interrogator can continuously broadcast thecarrier frequency.

Devices based on RFID or SAW technology can be used as switches in avehicle as described in U.S. Pat. No. 6,078,252, U.S. Pat. No. 6,144,288and U.S. Pat. No. 6,748,797. There are many ways that this can beaccomplished. A switch can be used to connect an antenna to either anRFID electronic device or to a SAW device. This of course requirescontacts to be closed by the switch activation. An alternate approach isto use pressure from an occupant's finger, for example, to alter theproperties of the acoustic wave on the SAW material much as in a SAWtouch screen. The properties that can be modified include the amplitudeof the acoustic wave, and its phase, and/or the time delay or anexternal impedance connected to one of the SAW reflectors as disclosedin U.S. Pat. No. 6,084,503. In this implementation, the SAW transducercan contain two sections, one which is modified by the occupant and theother which serves as a reference. A combined signal is sent to theinterrogator that decodes the signal to determine that the switch hasbeen activated. By any of these technologies, switches can bearbitrarily placed within the interior of an automobile, for example,without the need for wires. Since wires and connectors are the cause ofmost warranty repairs in an automobile, not only is the cost of switchessubstantially reduced but also the reliability of the vehicle electricalsystem is substantially improved.

The interrogation of switches can take place with moderate frequencysuch as once every 100 milliseconds. Either through the use of differentfrequencies or different delays, a large number of switches can be time,code, space and/or frequency multiplexed to permit separation of thesignals obtained by the interrogator. Alternately, an RF activatedswitch on some or all of the sensors can be used as discussed in moredetail below.

Another approach is to attach a variable impedance device across one ofthe reflectors on the SAW device. The impedance can therefore be used todetermine the relative reflection from the reflector compared to otherreflectors on the SAW device. In this manner, the magnitude as well asthe presence of a force exerted by an occupant's finger, for example,can be used to provide a rate sensitivity to the desired function. In analternate design, as shown U.S. Pat. No. 6,144,288, the switch is usedto connect the antenna to the SAW device. Of course, in this case, theinterrogator will not get a return from the SAW switch unless it isdepressed.

Temperature measurement is another field in which SAW technology can beapplied and the invention encompasses several embodiments of SAWtemperature sensors.

U.S. Pat. No. 4,249,418 is one of many examples of prior art SAWtemperature sensors. Temperature sensors are commonly used withinvehicles and many more applications might exist if a low cost wirelesstemperature sensor is available such as disclosed herein. The SAWtechnology can be used for such temperature sensing tasks. These tasksinclude measuring the vehicle coolant temperature, air temperaturewithin passenger compartment at multiple locations, seat temperature foruse in conjunction with seat warming and cooling systems, outsidetemperatures and perhaps tire surface temperatures to provide earlywarning to operators of road freezing conditions. One example, is toprovide air temperature sensors in the passenger compartment in thevicinity of ultrasonic transducers used in occupant sensing systems asdescribed in the current assignee's U.S. Pat. No. 5,943,295 (Varga etal.), since the speed of sound in the air varies by approximately 20%from −40° C. to 85° C. Current ultrasonic occupant sensor systems do notmeasure or compensate for this change in the speed of sound with theeffect of reducing the accuracy of the systems at the temperatureextremes. Through the judicious placement of SAW temperature sensors inthe vehicle, the passenger compartment air temperature can be accuratelyestimated and the information provided wirelessly to the ultrasonicoccupant sensor system thereby permitting corrections to be made for thechange in the speed of sound.

Since the road can be either a source or a sink of thermal energy,strategically placed sensors that measure the surface temperature of atire can also be used to provide an estimate of road temperature.

Acceleration sensing is another field in which SAW technology can beapplied and the invention encompasses several embodiments of SAWaccelerometers.

U.S. Pat. No. 4,199,990, U.S. Pat. No. 4,306,456 and U.S. Pat. No.4,549,436 are examples of prior art SAW accelerometers. Most airbagcrash sensors for determining whether the vehicle is experiencing afrontal or side impact currently use micromachined accelerometers. Theseaccelerometers are usually based on the deflection of a mass which issensed using either capacitive or piezoresistive technologies. SAWtechnology has previously not been used as a vehicle accelerometer orfor vehicle crash sensing. Due to the importance of this function, atleast one interrogator could be dedicated to this critical function.Acceleration signals from the crash sensors should be reported at leastpreferably every 100 microseconds. In this case, the dedicatedinterrogator would send an interrogation pulse to all crash sensoraccelerometers every 100 microseconds and receive staggered accelerationresponses from each of the SAW accelerometers wirelessly. Thistechnology permits the placement of multiple low-cost accelerometers atideal locations for crash sensing including inside the vehicle sidedoors, in the passenger compartment and in the frontal crush zone.Additionally, crash sensors can now be located in the rear of thevehicle in the crush zone to sense rear impacts. Since the accelerationdata is transmitted wirelessly, concern about the detachment or cuttingof wires from the sensors disappears. One of the main concerns, forexample, of placing crash sensors in the vehicle doors where they mostappropriately can sense vehicle side impacts, is the fear that an impactinto the A-pillar of the automobile would sever the wires from thedoor-mounted crash sensor before the crash was sensed. This problemdisappears with the current wireless technology of this invention. Iftwo accelerometers are placed at some distance from each other, the rollacceleration of the vehicle can be determined and thus the tendency ofthe vehicle to rollover can be predicted in time to automatically takecorrective action and/or deploy a curtain airbag or other airbag(s).Other types of sensors such as crash sensors based on pressuremeasurements, such as supplied by Siemens, can also now be wireless.

Although the sensitivity of measurement is considerably greater thanthat obtained with conventional piezo-electric or micromachinedaccelerometers, the frequency deviation of SAW devices remains low (inabsolute value). Accordingly, the frequency drift of thermal originshould be made as low as possible by selecting a suitable cut of thepiezoelectric material. The resulting accuracy is impressive aspresented in U.S. Pat. No. 4,549,436, which discloses an angularaccelerometer with a dynamic a range of 1 million, temperaturecoefficient of 0.005%/deg F. an accuracy of 1 microradian/sec², a powerconsumption of 1 milliwatt, a drift of 0.01% per year, a volume of 1cc/axis and a frequency response of 0 to 1000 Hz. The subject matter ofthe '436 patent is hereby included in the invention to constitute a partof the invention. A similar design can be used for acceleration sensing.

In a similar manner as the polymer-coated SAW device is used to measurepressure, a device wherein a seismic mass is attached to a SAW devicethrough a polymer interface can be made to sense acceleration. Thisgeometry has a particular advantage for sensing accelerations below 1 G,which has proved to be very difficult for conventional micro-machinedaccelerometers due to their inability to both measure low accelerationsand withstand high acceleration shocks.

Gyroscopes are another field in which SAW technology can be applied andthe inventions herein encompass several embodiments of SAW gyroscopes.

SAW technology is particularly applicable for gyroscopes as described inInternational Publication No. WO 00/79217A2 to Varadan et al. The outputof such gyroscopes can be determined with an interrogator that is alsoused for the crash sensor accelerometers, or a dedicated interrogatorcan be used. Gyroscopes having an accuracy of approximately 1 degree persecond have many applications in a vehicle including skid control andother dynamic stability functions. Additionally, gyroscopes of similaraccuracy can be used to sense impending vehicle rollover situations intime to take corrective action.

The inventors have represented that SAW gyroscopes of the type describedin WO 00/79217A2 have the capability of achieving accuracies approachingabout 3 degrees per hour. This high accuracy permits use of suchgyroscopes in an inertial measuring unit (IMU) that can be used withaccurate vehicle navigation systems and autonomous vehicle control basedon differential GPS corrections. Such a system is described in U.S. Pat.No. 6,370,475. An alternate preferred technology for an IMU is describedin U.S. Pat. No. 4,711,125 to Morrison discussed in more detail below.Such navigation systems depend on the availability of four or more GPSsatellites and an accurate differential correction signal such asprovided by the OmniStar Corporation, NASA or through the NationalDifferential GPS system now being deployed. The availability of thesesignals degrades in urban canyon environments, in tunnels and onhighways when the vehicle is in the vicinity of large trucks. For thisapplication, an IMU system should be able to accurately control thevehicle for perhaps 15 seconds and preferably for up to five minutes.IMUs based on SAW technology, the technology of U.S. Pat. No. 4,549,436discussed above or of the U.S. Pat. No. 4,711,125 are the best-knowndevices capable of providing sufficient accuracies for this applicationat a reasonable cost. Other accurate gyroscope technologies such asfiber optic systems are more accurate but can be cost-prohibitive,although recent analysis by the current assignee indicates that suchgyroscopes can eventually be made cost-competitive. In high volumeproduction, an IMU of the required accuracy based on SAW technology isestimated to cost less than about $100. A cost competing technology isthat disclosed in U.S. Pat. No. 4,711,125 which does not use SAWtechnology.

What follows is a discussion of the Morrison Cube of U.S. Pat. No.4,711,125 known as the QUBIK™. Let us review the typical problems thatare encountered with sensors that try to measure multiple physicalquantities at the same time and how the QUBIK solves these problems.These problems were provided by an IMU expert unfamiliar with the QUBIKand the responses are provided by Morrison.

1. Problem: Errors of measurement of the linear accelerations andangular speed are mutually correlated. Even if every one of the errors,taken separately, does not accumulate with integration (the inertialsystem's algorithm does that), the cross-coupled multiplication (such asone during re-projecting the linear accelerations from one coordinatesystem to another) will have these errors detected and will make them asystematic error similar to a sensor's bias.

Solution: The QUBIK IMU is calibrated and compensated for any cross axissensitivity. For example: if one of the angular accelerometer channelshas a sensitivity to any of the three of linear accelerations, then thelinear accelerations are buffered and scaled down and summed with thebuffered angular accelerometer output to cancel out all linearacceleration sensitivity on all three angular accelerometer channels.This is important to detect pure angular rate signals. This is a verycommon practice throughout the U.S. aerospace industry to makenavigation grade IMU's. Even when individual gyroscopes andaccelerometers are used in navigation, they have their outputs scaledand summed together to cancel out these cross axis errors. Note thatcompetitive MEMS products have orders of magnitude higher cross axissensitivities when compared to navigation grade sensors and they willundoubtedly have to use this practice to improve performance. MEMSangular rate sensors are advertised in degrees per second and navigationangular rate sensors are advertised in degrees per hour. MEMS angularrate sensors have high linear acceleration errors that must becompensated for at the IMU level.

2. Problem: The gyroscope and accelerometer channels require settings tobe made that contradict one another physically. For example, a gapbetween the cube and the housing for the capacitive sensors (thatmeasure the displacements of the cube) is not to exceed 50 to 100microns. On the other hand, the gyroscope channels require, in order toenhance a Coriolis effect used to measure the angular speed, that theamplitude and the linear speed of vibrations are as big as possible. Todo this, the gap and the frequency of oscillations should be increased.A greater frequency of oscillations in the nearly resonant mode requiresthe stiffness of the electromagnetic suspension to be increased, too,which leads to a worse measurement of the linear accelerations becausethe latter require that the rigidity of the suspension be minimal whenthere is a closed feedback.

Solution: The capacitive gap all around the levitated inner cube of theQUBIK is nominally 0.010 inches. The variable capacitance plates areexcited by a 1.5 MHz 25 volt peak to peak signal. The signal coming outis so strong (five volts) that there is no preamp required. Diodedetectors are mounted directly above the capacitive plates. There is noperformance change in the linear accelerometer channels when the angularaccelerometer channels are being dithered or rotated back and forthabout an axis. This was discovered by having a ground plane around theelectromagnets that eliminated transformer coupling. Dithering ordriving the angular accelerometer which rotates the inner cube proofmass is a gyroscopic displacement and not a linear displacement and hasno effect on the linear channels. Another very important point to makeis the servo loops measure the force required to keep the inner cube atits null and the servo loops are integrated to prevent anydisplacements. The linear accelerometer servo loops are not beingexercised to dither the inner cube. The angular accelerometer servo loopis being exercised. The linear and angular channels have their ownseparate set of capacitance detectors and electromagnets. Driving theangular channels has no effect on the linear ones.

The rigidity of an integrated closed loop servo is infinite at DC androlls off at higher frequencies. The QUBIK IMU measures the force beingapplied to the inner cube and not the displacement to measure angularrate. There is a force generated on the inner cube when it is beingrotated and the servo will not allow any displacement by applying equaland opposite forces on the inner cube to keep it at null. The servoreadout is a direct measurement of the gyroscopic forces on the innercube and not the displacement.

The servo gain is so high at the null position that one will not see thenull displacement but will see a current level equivalent to the forceon the cube. This is why integrated closed loop servos are so good. Theymeasure the force required to keep the inner cube at null and not thedisplacement. The angular accelerometer channel that is being ditheredwill have a noticeable displacement at its null. The sensor does nothave to be driven at its resonance. Driving the angular accelerometer atresonance will run the risk of over-driving the inner cube to the pointwhere it will bottom out and bang around inside its cavity. There is anactive gain control circuit to keep the alternating momentum constant.

Note that competitive MEMS based sensors are open loop and allowdisplacements which increase cross axis errors. MEMS sensors must havedisplacements to work and do not measure the Coriolis force, theymeasure displacement which results in huge cross axis sensitivityissues.

3. Problem: As the electromagnetic suspension is used, the sensor isgoing to be sensitive to external constant and variable (alternating)fields. Its errors will vary with its position, for example, withrespect to the Earth's magnetic field or other magnetic sources.

Solution: The earths magnetic field varies from −0.0 to +0.3 gauss andthe magnets have gauss levels over 10,000. The earth field can beshielded if necessary.

4. Problem: The QUBIT sensing element is relatively heavy so the sensoris likely to be sensitive to angular accelerations and impacts. Also,the temperature of the environment can affect the micron-sized gaps,magnetic fields of the permanent magnets, the resistance of theinductance coils etc., which will eventually increase the sensor errors.

Solution: The inner cube has a gap of 0.010 inches and does not changesignificantly over temperature.

The resistance of the coils is not a factor in the active closed loopservo. Anybody who make this statement does not know what they aretalking about. There is a stable one PPM/C current readout resistor inseries with the coil that measures the current passing through the coilwhich eliminates the temperature sensitivity of the coil resistance.

Permanent magnets have already proven themselves to be very stable overtemperature when used in active servo loops used in navigationgyroscopes and accelerometers.

Note that the sensitivity that the QUBIK IMU has achieved 0.01 degreesper hour.

5. Problem: High Cost. To produce the QUBIK, one may need to maintainmicron-sized gaps and highly clean surfaces for capacitive sensors; thedevices must be assembled in a dust-free room, and the device itselfmust be hermetic (otherwise dust or moisture will put the capacitivesensor and the electromagnetic suspension out of operation), thepermanent magnets must have a very stable performance because they'regoing to work in a feedback circuit, and so on. In our opinion, allthese issues make the technology overly complex and expensive, so anadditional metrological control will be required and no full automationcan be ever done.

Solution: The sensor does not have micron size gaps and does not need tobe hermetic unless the sensor is submerged in water! Most of the QUBIKIMU sensor is a cut out PCB's that can certainly be automated. The PCBdesign can keep dust out and does not need to be hermetic. Humidity isnot a problem unless the sensor is submerged in water. The permanentmagnets achieve parts per million stability at a cost of $0.05 each fora per system cost of under one dollar. There are may navigation gradegyroscopes and accelerometers that use permanent magnets.

Competitive MEMS sensors can of course have process contaminationproblems. To my knowledge, there are no MEMS angular rate sensors thatdo not require human labor and/or calibration. The QUBIK IMU can insteaduse programmable potentiometers at calibration instead of human labor.

Once an IMU of the accuracy described above is available in the vehicle,this same device can be used to provide significant improvements tovehicle stability control and rollover prediction systems.

Keyless entry systems are another field in which SAW technology can beapplied and the invention encompasses several embodiments of accesscontrol systems using SAW devices.

A common use of SAW or RFID technology is for access control tobuildings however, the range of electronic unpowered RFID technology isusually limited to one meter or less. In contrast, the SAW technology,when powered or boosted, can permit sensing up to about 30 meters. As akeyless entry system, an automobile can be configured such that thedoors unlock as the holder of a card containing the SAW ID systemapproaches the vehicle and similarly, the vehicle doors can beautomatically locked when the occupant with the card travels beyond acertain distance from the vehicle. When the occupant enters the vehicle,the doors can again automatically lock either through logic or through acurrent system wherein doors automatically lock when the vehicle isplaced in gear. An occupant with such a card would also not need to havean ignition key. The vehicle would recognize that the SAW-based card wasinside vehicle and then permit the vehicle to be started by issuing anoral command if a voice recognition system is present or by depressing abutton, for example, without the need for an ignition key.

Although they will not be discussed in detail, SAW sensors operating inthe wireless mode can also be used to sense for ice on the windshield orother exterior surfaces of the vehicle, condensation on the inside ofthe windshield or other interior surfaces, rain sensing, heat-loadsensing and many other automotive sensing functions. They can also beused to sense outside environmental properties and states includingtemperature, humidity, etc.

SAW sensors can be economically used to measure the temperature andhumidity at numerous places both inside and outside of a vehicle. Whenused to measure humidity inside the vehicle, a source of water vapor canbe activated to increase the humidity when desirable and the airconditioning system can be activated to reduce the humidity whennecessary or desirable. Temperature and humidity measurements outside ofthe vehicle can be an indication of potential road icing problems. Suchinformation can be used to provide early warning to a driver ofpotentially dangerous conditions. Although the invention describedherein is related to land vehicles, many of these advances are equallyapplicable to other vehicles such as airplanes and even, in some cases,homes and buildings. The invention disclosed herein, therefore, is notlimited to automobiles or other land vehicles.

Road condition sensing is another field in which SAW technology can beapplied and the invention encompasses several embodiments of SAW roadcondition sensors.

The temperature and moisture content of the surface of a roadway arecritical parameters in determining the icing state of the roadway.Attempts have been made to measure the coefficient of friction between atire and the roadway by placing strain gages in the tire tread.Naturally, such strain gages are ideal for the application of SAWtechnology especially since they can be interrogated wirelessly from adistance and they require no power for operation. As discussed herein,SAW accelerometers can also perform this function. The measurement ofthe friction coefficient, however, is not predictive and the vehicleoperator is only able to ascertain the condition after the fact. BoostedSAW or RFID based transducers have the capability of being interrogatedas much as 100 feet from the interrogator. Therefore, the judiciousplacement of low-cost powerless SAW or RFID temperature and humiditysensors in and/or on the roadway at critical positions can provide anadvance warning to vehicle operators that the road ahead is slippery.Such devices are very inexpensive and therefore could be placed atfrequent intervals along a highway.

An infrared sensor that looks down the highway in front of the vehiclecan actually measure the road temperature prior to the vehicle travelingon that part of the roadway. This system also would not give sufficientwarning if the operator waited for the occurrence of a frozen roadway.The probability of the roadway becoming frozen, on the other hand, canbe predicted long before it occurs, in most cases, by watching the trendin the temperature. Once vehicle-to-vehicle communications are common,roadway icing conditions can be communicated between vehicles.

Some lateral control of the vehicle can also be obtained from SAWtransducers or electronic RFID tags placed down the center of the lane,either above the vehicles and/or in the roadway, for example. A vehiclehaving two receiving antennas, for example, approaching such devices,through triangulation or direct proportion, is able to determine thelateral location of the vehicle relative to these SAW devices. If thevehicle also has an accurate map of the roadway, the identificationnumber associated with each such device can be used to obtain highlyaccurate longitudinal position determinations. Ultimately, the SAWdevices can be placed on structures beside the road and perhaps on everymile or tenth of a mile marker. If three antennas are used, as discussedherein, the distances from the vehicle to the SAW device can bedetermined. These SAW devices can be powered in order to stay belowcurrent FCC power transmission limits. Such power can be supplied by aphotocell, energy harvesting where applicable, by a battery or powerconnection.

Electronic RFID tags are also suitable for lateral and longitudinalpositioning purposes, however, the range available for currentelectronic RFID systems can be less than that of SAW-based systemsunless either are powered. On the other hand, as disclosed in U.S. Pat.No. 6,748,797, the time-of-flight of the RFID system can be used todetermine the distance from the vehicle to the RFID tag. Because of theinherent delay in the SAW devices and its variation with temperature,accurate distance measurement is probably not practical based ontime-of-flight but somewhat less accurate distance measurements based onrelative time-of-arrival can be made. Even if the exact delay imposed bythe SAW device was accurately known at one temperature, such devices areusually reasonably sensitive to changes in temperature, hence they makegood temperature sensors, and thus the accuracy of the delay in the SAWdevice is more difficult to maintain. An interesting variation of anelectronic RFID that is particularly applicable to this and otherapplications of this invention is described in A. Pohl, L. Reindl, “Newpassive sensors”, Proc. 16th IEEE Instrumentation and MeasurementTechnology Conf., IMTC/99, 1999, pp. 1251-1255.

Many SAW devices are based on lithium niobate or similar strongpiezoelectric materials. Such materials have high thermal expansioncoefficients. An alternate material is quartz that has a very lowthermal expansion coefficient. However, its piezoelectric properties areinferior to lithium niobate. One solution to this problem is to uselithium niobate as the coupling system between the antenna and thematerial or substrate upon which the surface acoustic wave travels. Inthis manner, the advantages of a low thermal expansion coefficientmaterial can be obtained while using the lithium niobate for its strongpiezoelectric properties. Other useful materials such as Langasite™ haveproperties that are intermediate between lithium niobate and quartz.

The use of SAW tags as an accurate precise positioning system asdescribed above would be applicable for accurate vehicle location, asdiscussed in U.S. Pat. No. 6,370,475, for lanes in tunnels, for example,or other cases where loss of satellite lock, and thus the primaryvehicle location system, is common.

The various technologies discussed above can be used in combination. Theelectronic RFID tag can be incorporated into a SAW tag providing asingle device that provides both a quick reflection of the radiofrequency waves as well as a re-transmission at a later time. Thismarriage of the two technologies permits the strengths of eachtechnology to be exploited in the same device. For most of theapplications described herein, the cost of mounting such a tag in avehicle or on the roadway far exceeds the cost of the tag itself.Therefore, combining the two technologies does not significantly affectthe cost of implementing tags onto vehicles or roadways or side highwaystructures.

A variation of this design is to use an RF circuit such as in an RFID toserve as an energy source. One design could be for the RFID to operatewith directional antennas at a relatively high frequency such as 2.4GHz. This can be primarily used to charge a capacitor to provide theenergy for boosting the signal from the SAW sensor using circuitry suchas a circulator discussed below. The SAW sensor can operate at a lowerfrequency, such as 400 MHz, permitting it to not interfere with theenergy transfer to the RF circuit and also permit the signal to travelbetter to the receiver since it will be difficult to align the antennaat all times with the interrogator. Also, by monitoring the reception ofthe RF signal, the angular position of the tire can be determined andthe SAW circuit designed so that it only transmits when the antennas arealigned or when the vehicle is stationary. Many other opportunities nowpresent themselves with the RF circuit operating at a differentfrequency from the SAW circuit which will now be obvious to one skilledin the art.

An alternate method to the electronic RFID tag is to simply use a radaror lidar reflector and measure the time-of-flight to the reflector andback. The reflector can even be made of a series of reflecting surfacesdisplaced from each other to achieve some simple coding. It should beunderstood that RFID antennas can be similarly configured. Animprovement would be to polarize the radiation and use a reflector thatrotates the polarization angle allowing the reflector to be more easilyfound among other reflecting objects.

Another field in which SAW technology can be applied is for“ultrasound-on-a-surface” type of devices. U.S. Pat. No. 5,629,681,assigned to the current assignee herein and incorporated by referenceherein, describes many uses of ultrasound in a tube. Many of theapplications are also candidates for ultrasound-on-a-surface devices. Inthis case, a micro-machined SAW device will in general be replaced by amuch larger structure.

Based on the frequency and power available, and on FCC limitations, SAWor RFID or similar devices can be designed to permit transmissiondistances of many feet especially if minimal power is available. SinceSAW and RFID devices can measure both temperature and humidity, they arealso capable of monitoring road conditions in front of and around avehicle. Thus, a properly equipped vehicle can determine the roadconditions prior to entering a particular road section if such SAWdevices are embedded in the road surface or on mounting structures closeto the road surface as shown at 60 in FIG. 5. Such devices could provideadvance warning of freezing conditions, for example. Although at 60miles per hour such devices may only provide a one second warning ifpowered or if the FCC revises permitted power levels, this can besufficient to provide information to a driver to prevent dangerousskidding. Additionally, since the actual temperature and humidity can bereported, the driver will be warned prior to freezing of the roadsurface. SAW device 60 is shown in detail in FIG. 5A. Withvehicle-to-vehicle communication, the road conditions can becommunicated as needed.

If a SAW device 63 is placed in a roadway, as illustrated in FIG. 6, andif a vehicle 68 has two receiving antennas 61 and 62, an interrogatorcan transmit a signal from either of the two antennas and at a latertime, the two antennas will receive the transmitted signal from the SAWdevice 63. By comparing the arrival time of the two received pulses, theposition of vehicle 68 on a lane of the roadway can preciselycalculated. If the SAW device 63 has an identification code encoded intothe returned signal generated thereby, then a processor in the vehicle68 can determine its position on the surface of the earth, provided aprecise map is available such as by being stored in the processor'smemory. If another antenna 66 is provided, for example, at the rear ofthe vehicle 68, then the longitudinal position of the vehicle 68 canalso be accurately determined as the vehicle 68 passes the SAW device63.

The SAW device 63 does not have to be in the center of the road.Alternate locations for positioning of the SAW device 63 are onoverpasses above the road and on poles such as 64 and 65 on theroadside. For such cases, a source of power may be required. Such asystem has an advantage over a competing system using radar andreflectors in that it is easier to measure the relative time between thetwo received pulses than it is to measure time-of-flight of a radarsignal to a reflector and back. Such a system operates in all weatherconditions and is known as a precise location system. Eventually, such aSAW device 63 can be placed every tenth of a mile along the roadway orat some other appropriate spacing. For the radar or laser radarreflection system, the reflectors can be active devices that provideenvironmental information in addition to location information to theinterrogating vehicle.

If a vehicle is being guided by a DGPS and an accurate map system suchas disclosed in U.S. Pat. No. 6,405,132 is used, a problem arises whenthe GPS receiver system looses satellite lock as would happen when thevehicle enters a tunnel, for example. If a precise location system asdescribed above is placed at the exit of the tunnel, then the vehiclewill know exactly where it is and can re-establish satellite lock in aslittle as one second rather than typically 15 seconds as might otherwisebe required. Other methods making use of the cell phone system can beused to establish an approximate location of the vehicle suitable forrapid acquisition of satellite lock as described in G. M. Djuknic, R. E.Richton “Geolocation and Assisted GPS”, Computer Magazine, February2001, IEEE Computer Society, which is incorporated by reference hereinin its entirety. An alternate location system is described in U.S. Pat.No. 6,480,788.

More particularly, geolocation technologies that rely exclusively onwireless networks such as time of arrival, time difference of arrival,angle of arrival, timing advance, and multipath fingerprinting, as isknown to those skilled in the art, offer a shorter time-to-first-fix(TTFF) than GPS. They also offer quick deployment and continuoustracking capability for navigation applications, without the addedcomplexity and cost of upgrading or replacing any existing GPS receiverin vehicles. Compared to either mobile-station-based, stand-alone GPS ornetwork-based geolocation, assisted-GPS (AGPS) technology offerssuperior accuracy, availability and coverage at a reasonable cost. AGPSfor use with vehicles can comprise a communications unit with a minimalcapability GPS receiver arranged in the vehicle, an AGPS server with areference GPS receiver that can simultaneously “see” the same satellitesas the communications unit and a wireless network infrastructureconsisting at least of base stations and a mobile switching center. Thenetwork can accurately predict the GPS signal the communication unitwill receive and convey that information to the mobile unit such as avehicle, greatly reducing search space size and shortening the TTFF fromminutes to a second or less. In addition, an AGPS receiver in thecommunication unit can detect and demodulate weaker signals than thosethat conventional GPS receivers require. Because the network performsthe location calculations, the communication unit only needs to containa scaled-down GPS receiver. It is accurate within about 15 meters whenthey are outdoors, an order of magnitude more sensitive thanconventional GPS. Of course with the additional of differentialcorrections and carrier phase corrections, the location accuracy can beimproved to centimeters.

Since an AGPS server can obtain the vehicle's position from the mobileswitching center, at least to the level of cell and sector, and at thesame time monitor signals from GPS satellites seen by mobile stations,it can predict the signals received by the vehicle for any given time.Specifically, the server can predict the Doppler shift due to satellitemotion of GPS signals received by the vehicle, as well as other signalparameters that are a function of the vehicle's location. In a typicalsector, uncertainty in a satellite signal's predicted time of arrival atthe vehicle is about ±5 μs, which corresponds to ±5 chips of the GPScoarse acquisition (C/A) code. Therefore, an AGPS server can predict thephase of the pseudorandom noise (PRN) sequence that the receiver shoulduse to despread the C/A signal from a particular satellite (each GPSsatellite transmits a unique PRN sequence used for range measurements)and communicate that prediction to the vehicle. The search space for theactual Doppler shift and PRN phase is thus greatly reduced, and the AGPSreceiver can accomplish the task in a fraction of the time required byconventional GPS receivers. Further, the AGPS server maintains aconnection with the vehicle receiver over the wireless link, so therequirement of asking the communication unit to make specificmeasurements, collect the results and communicate them back is easilymet. After despreading and some additional signal processing, an AGPSreceiver returns back “pseudoranges” (that is, ranges measured withouttaking into account the discrepancy between satellite and receiverclocks) to the AGPS server, which then calculates the vehicle'slocation. The vehicle can even complete the location fix itself withoutreturning any data to the server. Further discussion of cellularlocation-based systems can be found in Caffery, J. J. Wireless Locationin CDMA Cellular Radio Systems. Kluwer Academic Publishers, 1999, ISBN:0792377036.

Sensitivity assistance, also known as modulation wipe-off, providesanother enhancement to detection of GPS signals in the vehicle'sreceiver. The sensitivity-assistance message contains predicted databits of the GPS navigation message, which are expected to modulate theGPS signal of specific satellites at specified times. The mobile stationreceiver can therefore remove bit modulation in the received GPS signalprior to coherent integration. By extending coherent integration beyondthe 20-ms GPS data-bit period (to a second or more when the receiver isstationary and to 400 ms when it is fast-moving) this approach improvesreceiver sensitivity. Sensitivity assistance provides an additional3-to-4-dB improvement in receiver sensitivity. Because some of the gainprovided by the basic assistance (code phases and Doppler shift values)is lost when integrating the GPS receiver chain into a mobile system,this can prove crucial to making a practical receiver.

Achieving optimal performance of sensitivity assistance in TIA/EIA-95CDMA systems is relatively straightforward because base stations andmobiles synchronize with GPS time. Given that global system for mobilecommunication (GSM), time division multiple access (TDMA), or advancedmobile phone service (AMPS) systems do not maintain such stringentsynchronization, implementation of sensitivity assistance and AGPStechnology in general will require novel approaches to satisfy thetiming requirement. The standardized solution for GSM and TDMA adds timecalibration receivers in the field (location measurement units) that canmonitor both the wireless-system timing and GPS signals used as a timingreference.

Many factors affect the accuracy of geolocation technologies, especiallyterrain variations such as hilly versus flat and environmentaldifferences such as urban versus suburban versus rural. Other factors,like cell size and interference, have smaller but noticeable effects.Hybrid approaches that use multiple geolocation technologies appear tobe the most robust solution to problems of accuracy and coverage.

AGPS provides a natural fit for hybrid solutions since it uses thewireless network to supply assistance data to GPS receivers in vehicles.This feature makes it easy to augment the assistance-data message withlow-accuracy distances from receiver to base stations measured by thenetwork equipment. Such hybrid solutions benefit from the high densityof base stations in dense urban environments, which are hostile to GPSsignals. Conversely, rural environments, where base stations are tooscarce for network-based solutions to achieve high accuracy, provideideal operating conditions for AGPS because GPS works well there.

From the above discussion, AGPS can be a significant part of thelocation determining system on a vehicle and can be used to augmentother more accurate systems such as DGPS and a precise positioningsystem based on road markers or signature matching as discussed aboveand in patents assigned to Intelligent Technologies International.

SAW transponders can also be placed in the license plates 67 (FIG. 6) ofall vehicles at nominal cost. An appropriately equipped automobile canthen determine the angular location of vehicles in its vicinity. If athird antenna 66 is placed at the center of the vehicle front, then amore accurate indication of the distance to a license plate of apreceding vehicle can also be obtained as described above. Thus, onceagain, a single interrogator coupled with multiple antenna systems canbe used for many functions. Alternately, if more than one SAWtransponder is placed spaced apart on a vehicle and if two antennas areon the other vehicle, then the direction and position of theSAW-equipped vehicle can be determined by the receiving vehicle. Thevehicle-mounted SAW or RFID device can also transmit information aboutthe vehicle on which it is mounted such as the type of vehicle (car,van, SUV, truck, emergency vehicle etc.) as well as its weight and/ormass. One problem with many of the systems disclosed above results fromthe low power levels permitted by the FCC. Thus changes in FCCregulations may be required before some of them can be implemented in apowerless mode.

A general SAW temperature and pressure gage which can be wireless andpowerless is shown generally at 70 located in the sidewall 73 of a fluidcontainer 74 in FIG. 7. A pressure sensor 71 is located on the inside ofthe container 74, where it measures deflection of the container wall,and the fluid temperature sensor 72 on the outside. The temperaturemeasuring SAW 70 can be covered with an insulating material to avoid theinfluence of the ambient temperature outside of the container 74.

A SAW load sensor can also be used to measure load in the vehiclesuspension system powerless and wirelessly as shown in FIG. 8. FIG. 8Aillustrates a strut 75 such as either of the rear struts of the vehicleof FIG. 8. A coil spring 80 stresses in torsion as the vehicleencounters disturbances from the road and this torsion can be measuredusing SAW strain gages as described in U.S. Pat. No. 5,585,571 formeasuring the torque in shafts. This concept is also described in U.S.Pat. No. 5,714,695. The use of SAW strain gages to measure the torsionalstresses in a spring, as shown in FIG. 8B, and in particular in anautomobile suspension spring has, to the knowledge of the inventor, notbeen previously disclosed. In FIG. 8B, the strain measured by SAW straingage 78 is subtracted from the strain measured by SAW strain gage 77 toget the temperature compensated strain in spring 76.

Since a portion of the dynamic load is also carried by the shockabsorber, the SAW strain gages 77 and 78 will only measure the steady oraverage load on the vehicle. However, additional SAW strain gages 79 canbe placed on a piston rod 81 of the shock absorber to obtain the dynamicload. These load measurements can then be used for active or passivevehicle damping or other stability control purposes. Knowing the dynamicload on the vehicle coupled with measuring the response of the vehicleor of the load of an occupant on a seat also permits a determination ofthe vehicle's inertial properties and, in the case of the seat weightsensor, of the mass of an occupant and the state of the seat belt (is itbuckled and what load is it adding to the seat load sensors).

FIG. 9 illustrates a vehicle passenger compartment, and the enginecompartment, with multiple SAW or RFID temperature sensors 85. SAWtemperature sensors can be distributed throughout the passengercompartment, such as on the A-pillar, on the B-pillar, on the steeringwheel, on the seat, on the ceiling, on the headliner, and on thewindshield, rear and side windows and generally in the enginecompartment. These sensors, which can be independently coded withdifferent IDs and/or different delays, can provide an accuratemeasurement of the temperature distribution within the vehicle interior.RFID switches as discussed below can also be used to isolate one devicefrom another. Such a system can be used to tailor the heating and airconditioning system based on the temperature at a particular location inthe passenger compartment. If this system is augmented with occupantsensors, then the temperature can be controlled based on seat occupancyand the temperature at that location. If the occupant sensor system isbased on ultrasonics, then the temperature measurement system can beused to correct the ultrasonic occupant sensor system for the speed ofsound within the passenger compartment. Without such a correction, theerror in the sensing system can be as large as about 20 percent.

In one implementation, SAW temperature and other sensors can be madefrom PVDF film and incorporated within the ultrasonic transducerassembly. For the 40 kHz ultrasonic transducer case, for example, theSAW temperature sensor would return the several pulses sent to drive theultrasonic transducer to the control circuitry using the same wires usedto transmit the pulses to the transducer after a delay that isproportional to the temperature within the transducer housing. Thus, avery economical device can add this temperature sensing function usingmuch of the same hardware that is already present for the occupantsensing system. Since the frequency is low, PVDF could be fabricatedinto a very low cost temperature sensor for this purpose. Otherpiezoelectric materials can of course also be used.

Note, the use of PVDF as a piezoelectric material for wired and wirelessSAW transducers or sensors is an important disclosure of at least one ofthe inventions disclosed herein. Such PVDF SAW devices can be used aschemical, biological, temperature, pressure and other SAW sensors aswell as for switches. Such devices are very inexpensive to manufactureand are suitable for many vehicle-mounted devices as well as for othernon-vehicle-mounted sensors. Disadvantages of PVDF stem from the lowerpiezoelectric constant (compared with lithium niobate) and the lowacoustic wave velocity thus limiting the operating frequency. The keyadvantage is very low cost. When coupled with plastic electronics(plastic chips), it now becomes very economical to place sensorsthroughout the vehicle for monitoring a wide range of parameters such astemperature, pressure, chemical concentration etc. In particularimplementations, an electronic nose based on SAW or RFID technology andneural networks can be implemented in either a wired or wireless mannerfor the monitoring of cargo containers or other vehicle interiors (orbuilding interiors) for anti-terrorist or security purposes. See, forexample, Reznik, A. M. “Associative Memories for Chemical Sensing”, IEEE2002 ICONIP, p. 2630-2634, vol. 5. In this manner, other sensors can becombined with the temperature sensors 85, or used separately, to measurecarbon dioxide, carbon monoxide, alcohol, biological agents, radiation,humidity or other desired chemicals or agents as discussed above. Note,although the examples generally used herein are from the automotiveindustry, many of the devices disclosed herein can be advantageouslyused with other vehicles including trucks, boats, airplanes and shippingcontainers.

The SAW temperature sensors 85 provide the temperature at their mountinglocation to a processor unit 83 via an interrogator with the processorunit 83 including appropriate control algorithms for controlling theheating and air conditioning system based on the detected temperatures.The processor unit 83 can control, e.g., which vents in the vehicle areopen and closed, the flow rate through vents and the temperature of airpassing through the vents. In general, the processor unit 83 can controlwhatever adjustable components are present or form part of the heatingand air conditioning system.

In FIG. 9 a child seat 84 is illustrated on the rear vehicle seat. Thechild seat 84 can be fabricated with one or more RFID tags or SAW tags(not shown). The RFID and SAW tag(s) can be constructed to provideinformation on the occupancy of the child seat, i.e., whether a child ispresent, based on the weight, temperature, and/or any other measurableparameter. Also, the mere transmission of waves from the RFID or SAWtag(s) on the child seat 84 would be indicative of the presence of achild seat. The RFID and SAW tag(s) can also be constructed to provideinformation about the orientation of the child seat 84, i.e., whether itis facing rearward or forward. Such information about the presence andoccupancy of the child seat and its orientation can be used in thecontrol of vehicular systems, such as the vehicle airbag system orheating or air conditioning system, especially useful when a child isleft in a vehicle. In this case, a processor would control the airbag orHVAC system and would receive information from the RFID and SAW tag(s)via an interrogator.

There are many applications for which knowledge of the pitch and/or rollorientation of a vehicle or other object is desired. An accurate tiltsensor can be constructed using SAW devices. Such a sensor isillustrated in FIG. 10A and designated 86. This sensor 86 can utilize asubstantially planar and rectangular mass 87 and four supporting SAWdevices 88 which are sensitive to gravity. For example, the mass 87 actsto deflect a membrane on which the SAW device 88 resides therebystraining the SAW device 88. Other properties can also be used for atilt sensor such as the direction of the earth's magnetic field. SAWdevices 88 are shown arranged at the corners of the planar mass 87, butit must be understood that this arrangement is an exemplary embodimentonly and not intended to limit the invention. A fifth SAW device 89 canbe provided to measure temperature. By comparing the outputs of the fourSAW devices 88, the pitch and roll of the automobile can be measured.This sensor 86 can be used to correct errors in the SAW rate gyrosdescribed above. If the vehicle has been stationary for a period oftime, the yaw SAW rate gyro can initialized to 0 and the pitch and rollSAW gyros initialized to a value determined by the tilt sensor of FIG.10A. Many other geometries of tilt sensors utilizing one or more SAWdevices can now be envisioned for automotive and other applications.

In particular, an alternate preferred configuration is illustrated inFIG. 10B where a triangular geometry is used. In this embodiment, theplanar mass is triangular and the SAW devices 88 are arranged at thecorners, although as with FIG. 10A, this is a non-limiting, preferredembodiment.

Either of the SAW accelerometers described above can be utilized forcrash sensors as shown in FIG. 11. These accelerometers have asubstantially higher dynamic range than competing accelerometers nowused for crash sensors such as those based on MEMS silicon springs andmasses and others based on MEMS capacitive sensing. As discussed above,this is partially a result of the use of frequency or phase shifts whichcan be measured over a very wide range. Additionally, many conventionalaccelerometers that are designed for low acceleration ranges are unableto withstand high acceleration shocks without breaking. This placespractical limitations on many accelerometer designs so that the stressesin the silicon are not excessive. Also for capacitive accelerometers,there is a narrow limit over which distance, and thus acceleration, canbe measured.

The SAW accelerometer for this particular crash sensor design is housedin a container 96 which is assembled into a housing 97 and covered witha cover 98. This particular implementation shows a connector 99indicating that this sensor would require power and the response wouldbe provided through wires. Alternately, as discussed for other devicesabove, the connector 99 can be eliminated and the information and powerto operate the device transmitted wirelessly. Also, power can besupplied thorough a connector and stored in a capacitor while theinformation is transmitted wirelessly thus protecting the system from awire failure during a crash when the sensor is mounted in the crushzone. Such sensors can be used as frontal, side or rear impact sensors.They can be used in the crush zone, in the passenger compartment or anyother appropriate vehicle location. If two such sensors are separatedand have appropriate sensitive axes, then the angular acceleration ofthe vehicle can also be determined. Thus, for example, forward-facingaccelerometers mounted in the vehicle side doors can be used to measurethe yaw acceleration of the vehicle. Alternately, two vertical sensitiveaxis accelerometers in the side doors can be used to measure the rollacceleration of vehicle, which would be useful for rollover sensing.

U.S. Pat. No. 6,615,656, assigned to the current assignee of thisinvention, and the description below, provides multiple apparatus fordetermining the amount of liquid in a tank. Using the SAW pressuredevices of this invention, multiple pressure sensors can be placed atappropriate locations within a fuel tank to measure the fluid pressureand thereby determine the quantity of fuel remaining in the tank. Thiscan be done both statically and dynamically. This is illustrated in FIG.12. In this example, four SAW pressure transducers 100 are placed on thebottom of the fuel tank and one SAW pressure transducer 101 is placed atthe top of the fuel tank to eliminate the effects of vapor pressurewithin tank. Using neural networks, or other pattern recognitiontechniques, the quantity of fuel in the tank can be accuratelydetermined from these pressure readings in a manner similar to thatdescribed the '656 patent and below. The SAW measuring deviceillustrated in FIG. 12A combines temperature and pressure measurementsin a single unit using parallel paths 102 and 103 in the same manner asdescribed above.

FIG. 13A shows a schematic of a prior art airbag module deploymentscheme in which sensors, which detect data for use in determiningwhether to deploy an airbag in the airbag module, are wired to anelectronic control unit (ECU) and a command to initiate deployment ofthe airbag in the airbag module is sent wirelessly. By contrast, asshown in FIG. 13B, in accordance with an invention herein, the sensorsare wirelessly connected to the electronic control unit and thustransmit data wirelessly. The ECU is however wired to the airbag module.The ECU could also be connected wirelessly to the airbag module.Alternately, a safety bus can be used in place of the wirelessconnection.

SAW sensors also have applicability to various other sectors of thevehicle, including the powertrain, chassis, and occupant comfort andconvenience. For example, SAW and RFID sensors have applicability tosensors for the powertrain area including oxygen sensors, gear-toothHall effect sensors, variable reluctance sensors, digital speed andposition sensors, oil condition sensors, rotary position sensors, lowpressure sensors, manifold absolute pressure/manifold air temperature(MAP/MAT) sensors, medium pressure sensors, turbo pressure sensors,knock sensors, coolant/fluid temperature sensors, and transmissiontemperature sensors.

SAW sensors for chassis applications include gear-tooth Hall effectsensors, variable reluctance sensors, digital speed and positionsensors, rotary position sensors, non-contact steering position sensors,and digital ABS (anti-lock braking system) sensors. In oneimplementation, a Hall Effect tire pressure monitor comprises a magnetthat rotates with a vehicle wheel and is sensed by a Hall Effect devicewhich is attached to a SAW or RFID device that is wirelesslyinterrogated. This arrangement eliminates the need to run a wire intoeach wheel well.

SAW sensors for the occupant comfort and convenience field include lowtire pressure sensors, HVAC temperature and humidity sensors, airtemperature sensors, and oil condition sensors.

SAW sensors also have applicability such areas as controllingevaporative emissions, transmission shifting, mass air flow meters,oxygen, NOx and hydrocarbon sensors. SAW based sensors are particularlyuseful in high temperature environments where many other technologiesfail.

SAW sensors can facilitate compliance with U.S. regulations concerningevaporative system monitoring in vehicles, through a SAW fuel vaporpressure and temperature sensors that measure fuel vapor pressure withinthe fuel tank as well as temperature. If vapors leak into theatmosphere, the pressure within the tank drops. The sensor notifies thesystem of a fuel vapor leak, resulting in a warning signal to the driverand/or notification to a repair facility, vehicle manufacturer and/orcompliance monitoring facility. This application is particularlyimportant since the condition within the fuel tank can be ascertainedwirelessly reducing the chance of a fuel fire in an accident. The sameinterrogator that monitors the tire pressure SAW sensors can alsomonitor the fuel vapor pressure and temperature sensors resulting insignificant economies.

A SAW humidity sensor can be used for measuring the relative humidityand the resulting information can be input to the engine managementsystem or the heating, ventilation and air conditioning (HVAC) systemfor more efficient operation. The relative humidity of the air enteringan automotive engine impacts the engine's combustion efficiency; i.e.,the ability of the spark plugs to ignite the fuel/air mixture in thecombustion chamber at the proper time. A SAW humidity sensor in thiscase can measure the humidity level of the incoming engine air, helpingto calculate a more precise fuel/air ratio for improved fuel economy andreduced emissions.

Dew point conditions are reached when the air is fully saturated withwater. When the cabin dew point temperature matches the windshield glasstemperature, water from the air condenses quickly, creating frost orfog. A SAW humidity sensor with a temperature-sensing element and awindow glass-temperature-sensing element can prevent the formation ofvisible fog formation by automatically controlling the HVAC system.

FIG. 14 illustrates the placement of a variety of sensors, primarilyaccelerometers and/or gyroscopes, which can be used to diagnose thestate of the vehicle itself. Sensor 105 can be located in the headlineror attached to the vehicle roof above the side door. Typically, therecan be two such sensors one on either side of the vehicle. Sensor 106 isshown in a typical mounting location midway between the sides of thevehicle attached to or near the vehicle roof above the rear window.Sensor 109 is shown in a typical mounting location in the vehicle trunkadjacent the rear of the vehicle. One, two or three such sensors can beused depending on the application. If three such sensors are used,preferably one would be adjacent each side of vehicle and one in thecenter. Sensor 107 is shown in a typical mounting location in thevehicle door and sensor 108 is shown in a typical mounting location onthe sill or floor below the door. Sensor 110, which can be also multiplesensors, is shown in a typical mounting location forward in the crushzone of the vehicle. Finally, sensor 111 can measure the acceleration ofthe firewall or instrument panel and is located thereon generally midwaybetween the two sides of the vehicle. If three such sensors are used,one would be adjacent each vehicle side and one in the center. An IMUwould serve basically the same functions.

In general, sensors 105-111 provide a measurement of the state of thevehicle, such as its velocity, acceleration, angular orientation ortemperature, or a state of the location at which the sensor is mounted.Thus, measurements related to the state of the sensor would includemeasurements of the acceleration of the sensor, measurements of thetemperature of the mounting location as well as changes in the state ofthe sensor and rates of changes of the state of the sensor. As such, anydescribed use or function of the sensors 105-111 above is merelyexemplary and is not intended to limit the form of the sensor or itsfunction. Thus, these sensors may or may not be SAW or RFID sensors andmay be powered or unpowered and may transmit their information through awire harness, a safety or other bus or wirelessly.

Each of the sensors 105-111 may be single axis, double axis or triaxialaccelerometers and/or gyroscopes typically of the MEMS type. One or morecan be IMUs. These sensors 105-111 can either be wired to the centralcontrol module or processor directly wherein they would receive powerand transmit information, or they could be connected onto the vehiclebus or, in some cases, using RFID, SAW or similar technology, thesensors can be wireless and would receive their power through RF fromone or more interrogators located in the vehicle. In this case, theinterrogators can be connected either to the vehicle bus or directly tocontrol module. Alternately, an inductive or capacitive power and/orinformation transfer system can be used.

One particular implementation will now be described. In this case, eachof the sensors 105-111 is a single or dual axis accelerometer. They aremade using silicon micromachined technology such as described in U.S.Pat. No. 5,121,180 and U.S. Pat. No. 5,894,090. These are onlyrepresentative patents of these devices and there exist more than 100other relevant U.S. patents describing this technology. Commerciallyavailable MEMS gyroscopes such as from Systron Doner have accuracies ofapproximately one degree per second. In contrast, optical gyroscopestypically have accuracies of approximately one degree per hour.Unfortunately, the optical gyroscopes are believed to be expensive forautomotive applications. However new developments by the currentassignee are reducing this cost and such gyroscopes are likely to becomecost effective in a few years. On the other hand, typical MEMSgyroscopes are not sufficiently accurate for many control applicationsunless corrected using location technology such as precise positioningor GPS-based systems as described elsewhere herein.

The angular rate function can be obtained by placing accelerometers attwo separated, non-co-located points in a vehicle and using thedifferential acceleration to obtain an indication of angular motion andangular acceleration. From the variety of accelerometers shown in FIG.14, it can be appreciated that not only will all accelerations of keyparts of the vehicle be determined, but the pitch, yaw and roll angularrates can also be determined based on the accuracy of theaccelerometers. By this method, low cost systems can be developed which,although not as accurate as the optical gyroscopes, are considerablymore accurate than uncorrected conventional MEMS gyroscopes.Alternately, it has been found that from a single package containing upto three low cost MEMS gyroscopes and three low cost MEMSaccelerometers, when carefully calibrated, an accurate inertialmeasurement unit (IMU) can be constructed that performs as well as unitscosting a great deal more. Such a package is sold by CrossbowTechnology, Inc. 41 Daggett Dr., San Jose, Calif. 95134. If this IMU iscombined with a GPS system and sometimes other vehicle sensor inputsusing a Kalman filter, accuracy approaching that of expensive militaryunits can be achieved. A preferred IMU that uses a single device tosense both accelerations in three directions and angular rates aboutthree axis is described in U.S. Pat. No. 4,711,125. Although this devicehas been available for many years, it has not been applied to vehiclesensing and in particular automobile vehicle sensing for location andnavigational purposes.

Instead of using two accelerometers at separate locations on thevehicle, a single conformal MEMS-IDT gyroscope may be used. Such aconformal MEMS-IDT gyroscope is described in a paper by V. K. Varadan,“Conformal MEMS-IDT Gyroscopes and Their Comparison With Fiber OpticGyro”, Proceedings of SPIE Vol. 3990 (2000). The MEMS-IDT gyroscope isbased on the principle of surface acoustic wave (SAW) standing waves ona piezoelectric substrate. A surface acoustic wave resonator is used tocreate standing waves inside a cavity and the particles at theanti-nodes of the standing waves experience large amplitude ofvibrations, which serves as the reference vibrating motion for thegyroscope. Arrays of metallic dots are positioned at the anti-nodelocations so that the effect of Coriolis force due to rotation willacoustically amplify the magnitude of the waves. Unlike other MEMSgyroscopes, the MEMS-IDT gyroscope has a planar configuration with nosuspended resonating mechanical structures. Other SAW-based gyroscopesare also now under development.

The system of FIG. 14 using dual axis accelerometers, or the IMU Kalmanfilter system, therefore provides a complete diagnostic system of thevehicle itself and its dynamic motion. Such a system is far moreaccurate than any system currently available in the automotive market.This system provides very accurate crash discrimination since the exactlocation of the crash can be determined and, coupled with knowledge ofthe force deflection characteristics of the vehicle at the accidentimpact site, an accurate determination of the crash severity and thusthe need for occupant restraint deployment can be made. Similarly, thetendency of a vehicle to rollover can be predicted in advance andsignals sent to the vehicle steering, braking and throttle systems toattempt to ameliorate the rollover situation or prevent it. In the eventthat it cannot be prevented, the deployment side curtain airbags can beinitiated in a timely manner. Additionally, the tendency of the vehicleto the slide or skid can be considerably more accurately determined andagain the steering, braking and throttle systems commanded to minimizethe unstable vehicle behavior. Thus, through the deployment ofinexpensive accelerometers at a variety of locations in the vehicle, orthe IMU Kalman filter system, significant improvements are made invehicle stability control, crash sensing, rollover sensing and resultingoccupant protection technologies.

As mentioned above, the combination of the outputs from theseaccelerometer sensors and the output of strain gage weight sensors in avehicle seat, or in or on a support structure of the seat, can be usedto make an accurate assessment of the occupancy of the seat anddifferentiate between animate and inanimate occupants as well asdetermining where in the seat the occupants are sitting. This can bedone by observing the acceleration signals from the sensors of FIG. 14and simultaneously the dynamic strain gage measurements fromseat-mounted strain gages. The accelerometers provide the input functionto the seat and the strain gages measure the reaction of the occupyingitem to the vehicle acceleration and thereby provide a method ofdetermining dynamically the mass of the occupying item and its location.This is particularly important during occupant position sensing during acrash event. By combining the outputs of the accelerometers and thestrain gages and appropriately processing the same, the mass and weightof an object occupying the seat can be determined as well as the grossmotion of such an object so that an assessment can be made as to whetherthe object is a life form such as a human being.

For this embodiment, a sensor, not shown, that can be one or more straingage weight sensors, is mounted on the seat or in connection with theseat or its support structure. Suitable mounting locations and forms ofweight sensors are discussed in the current assignee's U.S. Pat. No.6,242,701 and contemplated for use in the inventions disclosed herein aswell. The mass or weight of the occupying item of the seat can thus bemeasured based on the dynamic measurement of the strain gages withoptional consideration of the measurements of accelerometers on thevehicle, which are represented by any of sensors 105-111.

A SAW Pressure Sensor can also be used with bladder weight sensorspermitting that device to be interrogated wirelessly and without theneed to supply power. Similarly, a SAW device can be used as a generalswitch in a vehicle and in particular as a seatbelt buckle switchindicative of seatbelt use. SAW devices can also be used to measureseatbelt tension or the acceleration of the seatbelt adjacent to thechest or other part of the occupant and used to control the occupant'sacceleration during a crash. Such systems can be boosted as disclosedherein or not as required by the application. These inventions aredisclosed in patents and patent applications of the current assignee.

The operating frequency of SAW devices has hereto for been limited toless that about 500 MHz due to problems in lithography resolution, whichof course is constantly improving and currently SAW devices based onlithium niobate are available that operate at 2.4 GHz. This lithographyproblem is related to the speed of sound in the SAW material. Diamondhas the highest speed of sound and thus would be an ideal SAW material.However, diamond is not piezoelectric. This problem can be solvedpartially by using a combination or laminate of diamond and apiezoelectric material. Recent advances in the manufacture of diamondfilms that can be combined with a piezoelectric material such as lithiumniobate promise to permit higher frequencies to be used since thespacing between the inter-digital transducer (IDT) fingers can beincreased for a given frequency. A particularly attractive frequency is2.4 GHz or Wi-Fi as the potential exists for the use of moresophisticated antennas such as the Yagi antenna or the Motia smartantenna that have more gain and directionality. In a differentdevelopment, SAW devices have been demonstrated that operate in the tensof GHz range using a novel stacking method to achieve the close spacingof the IDTs.

In a related invention, the driver can be provided with a keyless entrydevice, other RFID tag, smart card or cell phone with an RF transponderthat can be powerless in the form of an RFID or similar device, whichcan also be boosted as described herein. The interrogator determines theproximity of the driver to the vehicle door or other similar object suchas a building or house door or vehicle trunk. As shown in FIG. 15A, if adriver 118 remains within 1 meter, for example, from the door or trunklid 116, for example, for a time period such as 5 seconds, then the dooror trunk lid 116 can automatically unlock and ever open in someimplementations. Thus, as the driver 118 approaches the trunk with hisor her arms filled with packages 117 and pauses, the trunk canautomatically open (see FIG. 15B). Such a system would be especiallyvaluable for older people. Naturally, this system can also be used forother systems in addition to vehicle doors and trunk lids.

As shown in FIG. 15C, an interrogator 115 is placed on the vehicle,e.g., in the trunk 112 as shown, and transmits waves. When the keylessentry device 113, which contains an antenna 114 and a circuit includinga circulator 135 and a memory containing a unique ID code 136, is a setdistance from the interrogator 115 for a certain duration of time, theinterrogator 115 directs a trunk opening device 137 to open the trunklid 116

A SAW device can also be used as a wireless switch as shown in FIGS. 16Aand 16B. FIG. 16A illustrates a surface 120 containing a projection 122on top of a SAW device 121. Surface material 120 could be, for example,the armrest of an automobile, the steering wheel airbag cover, or anyother surface within the passenger compartment of an automobile orelsewhere. Projection 122 will typically be a material capable oftransmitting force to the surface of SAW device 121. As shown in FIG.20B, a projection 123 may be placed on top of the SAW device 124. Thisprojection 123 permits force exerted on the projection 122 to create apressure on the SAW device 124. This increased pressure changes the timedelay or natural frequency of the SAW wave traveling on the surface ofmaterial. Alternately, it can affect the magnitude of the returnedsignal. The projection 123 is typically held slightly out of contactwith the surface until forced into contact with it.

An alternate approach is to place a switch across the IDT 127 as shownin FIG. 16C. If switch 125 is open, then the device will not return asignal to the interrogator. If it is closed, than the IDT 127 will actas a reflector sending a signal back to IDT 128 and thus to theinterrogator. Alternately, a switch 126 can be placed across the SAWdevice. In this case, a switch closure shorts the SAW device and nosignal is returned to the interrogator. For the embodiment of FIG. 16C,using switch 126 instead of switch 125, a standard reflector IDT wouldbe used in place of the IDT 127.

FIG. 16D shows an embodiment wherein a radio-frequency identificationdevice (RFID) is controlled by a switch 129A, and may be one of thewireless transmission components of a switch assembly. The switch 129Amay be a conventional, mechanical switch such as a push button, toggleand the like. A switch assembly would therefore comprise the RFID, theswitch 129A and an antenna 119A which may constitute another a wirelesstransmission component. In this case, when the user presses on anexposed surface of the passenger compartment, he or she would close theswitch 129A and thereby short the RFID so that it would be inoperative.That is, the RFID would not respond when interrogated. Instead of aswitch, a variable impedance could also be provided which would modifythe output of the RFID based on the magnitude of pressure to the exposedsurface. Instead of using the switch or variable impedance, anothercontrol mechanism for causing variation in the transmission by thewireless transmission components of the switch assembly can be provided.In this embodiment, as well as the other embodiments herein wherein anRFID is provided, the RFID can be either a passive RFID or an activeRFID. In the latter case, the RFID is supplied with power from a powersource on the vehicle, such as the vehicle's battery, a local battery,photo cell, or a local energy generator or harvester.

FIG. 16E shows an embodiment wherein a surface-acoustic-wave (SAW)device is controlled by a switch 129B, and may be one of the wirelesstransmission components of a switch assembly. The switch 129B may be aconventional, mechanical switch such as a push button, toggle and thelike. A switch assembly would therefore comprise the SAW device, theswitch 129B and an antenna 119B which may constitute another a wirelesstransmission component. In this case, when the user presses on anexposed surface of the passenger compartment, he or she would close theswitch 129B and thereby prevent the SAW device from receiving a signalso that it would be inoperative. Instead of a switch, a variableimpedance could also be provided which would modify the output of theSAW device based on the magnitude of pressure to the exposed surface.Instead of using the switch or variable impedance, another controlmechanism for causing variation in the transmission by the wirelesstransmission components of the switch assembly can be provided. In thisembodiment, as well as the other embodiments herein wherein a SAW deviceis provided, the SAW device can be either a passive SAW device or anactive SAW device. In the latter case, the SAW device is supplied withpower from a power source on the vehicle, such as the vehicle's battery,a local battery or a local energy generator or harvester.

A variable impedance is used as the control mechanism for situationswhen variations in the operation of a vehicular component are desired.For example, if a light is capable of being dimmed, then the variableimpedance would be useful to control the dimming of the light. It isalso useful to control adjustment of the volume of a sound system in thevehicle, as well as other analogue functions.

Referring now to FIG. 16F, another embodiment of the invention using acontrol mechanism, i.e., a switch or variable impedance, is an antenna139 capable of reflecting an interrogating signal, and even whichslightly modifies the interrogating signal (reflection from such anantenna being termed backscatter). The modification to the interrogatingsignal can be correlated to the desired manner for controlling thevehicular component. In this case, a lead is connected to anintermediate location on the antenna 139, e.g., the middle of theantenna 139, and a switch or variable impedance (a switch 129C is shown)is placed between the lead and ground. In the embodiment having a switch129C, when the switch 129C is open, the antenna 139 will reflect at aparticular frequency based on its length (for a simple dipole antenna).When the switch 129C is closed by the application of pressure to theexposed surface 138 of the passenger compartment, the antenna 139 willshort and thereby effectively reduce the length of the antenna 139 andalter the resonant frequency of the antenna 139. A lead placed at themiddle of the antenna 139 would, when connected to a closed switch 129Cleading to ground, cause the resonant frequency to approximately double.In the embodiment having variable impedance, the antenna would beprovided with a variable effect depending on the pressure exerted on theexposed surface or otherwise controlling the variable impedance.

Referring now to FIG. 16G, in another embodiment of a SAW sensorassembly in accordance with the invention, the circuit of the SAW sensorassembly has both an active mode and a passive mode depending on thepresence of sufficient power in the energy storage device and whetherthe substrate to which the SAW sensor assembly is associated with ismoving and thereby generates energy (for example, the energy may begenerated using the power generating system described below withreference to FIGS. 36, 36A and 98). That is, the SAW sensor assemblycircuit is provided with a passive mode, which is used when power is notprovided to the SAW device 158 by either an energy harvester or energygenerating system and the substrate (tire) is not moving, and an activemode when power is provided or available to the SAW device 158, e.g.,provided by an energy harvester or energy generating system uponrotation of the tire or from an energy storage device. In the activemode (when the tire is rotating or there is sufficient power in theenergy storage device to power the SAW device 158), a power detectioncircuit 157 detects power and closes a switch 129E thereby connectingthe SAW device 158 to the antenna 119C. Power detection circuit 157 maybe integrated into the SAW sensor assembly circuit so that wheneverthere is sufficient power being generated or available, the switch 129Eis automatically closed. On the other hand, when energy for the SAWdevice 158 is not provided by an energy storage device and the tire isnot rotating, switch 129E is open so as to avoid providing unnecessarysignals from the SAW device 158 to the interrogator via the antenna119C, the interrogator being used to obtain the signals from the SAWdevice 158 and process them into a meaningful reading of whateverproperty or properties is/are being monitored by the SAW device 158.However, since it is desirable to provide signals from the SAW device158 for certain conditions of the property being monitored by the SAWdevice 158, e.g., the property is below a threshold, a sensor 156 isprovided and controls a second switch 129D between the antenna 119C andthe SAW device 158. Sensor 156 is designed to close the switch when oneor more conditions relating to the property are satisfied to therebyenable a transmission from the antenna 119C to the SAW device 158 and amodified signal to be provided from the SAW device 158 to the antenna119C for transmission to the interrogator.

For example, if sensor 156 is a pressure sensor and SAW assembly isbeing used to monitor tire pressure, then when the pressure is below athreshold as detected by sensor 156, switch 129D is closed and therebyallows the SAW device 158 to provide a modified signal. Sensor 156should ideally be a sensor that does not require power (or requiresminimal power) and can continually monitor the property, for example, apressure sensing diaphragm could be used to and positioned relative tothe switch 129D so that when the pressure is below a threshold, thediaphragm moves and causes closure of the switch 129D. Indeed, theswitch 129D could even be attached to such a pressure sensing diaphragm.In this case, when the pressure is at or above the threshold, thepressure sensing diaphragm does not close switch 129D thereby conservingpower. Switch 129D would therefore be in an open position whenever thepressure was at or above the design threshold. Instead of a fixedthreshold, a variable threshold can be used based on any number offactors. Also, a temperature sensor could be used to close a switch iftemperature is being monitored, e.g., a diaphragm which expands withtemperature could be attached to the switch 129D or another thermal ortemperature switch used in the circuit. Any other type of sensor whichchanges its state or condition and can cause closure of a switch basedon a predetermined threshold, or switch which is activated based on asensed property of the tire, could also be used in the invention.

The minimal transmission from the SAW device 158 is necessary inparticular in a case where only one tire has a low pressure. One reasonfor this is because it is difficult to separate transmissions from morethan one tire when operating in the passive mode.

Most SAW-based accelerometers work on the principle of straining the SAWsurface and thereby changing either the time delay or natural frequencyof the system. An alternate novel accelerometer is illustrated FIG. 17Awherein a mass 130 is attached to a silicone rubber coating 131 whichhas been applied the SAW device. Acceleration of the mass in FIG. 17A inthe direction of arrow X changes the amount of rubber in contact withthe surface of the SAW device and thereby changes the damping, naturalfrequency or the time delay of the device. By this method, accuratemeasurements of acceleration below 1 G are readily obtained.Furthermore, this device can withstand high deceleration shocks withoutdamage. FIG. 17B illustrates a more conventional approach where thestrain in a beam 132 caused by the acceleration acting on a mass 133 ismeasured with a SAW strain sensor 134.

It is important to note that all of these devices have a high dynamicrange compared with most competitive technologies. In some cases, thisdynamic range can exceed 100,000 and up to 1,000,000 has been reported.This is the direct result of the ease with which frequency and phase canbe accurately measured.

A gyroscope, which is suitable for automotive applications, isillustrated in FIG. 18 and described in detail in Varadan U.S. Pat. No.6,516,665. This SAW-based gyroscope has applicability for the vehiclenavigation, dynamic control, and rollover sensing among others.

Note that any of the disclosed applications can be interrogated by thecentral interrogator of this invention and can either be powered oroperated powerlessly as described in general above. Block diagrams ofthree interrogators suitable for use in this invention are illustratedin FIGS. 19A-19C. FIG. 19A illustrates a super heterodyne circuit andFIG. 19B illustrates a dual super heterodyne circuit. FIG. 19C operatesas follows. During the burst time two frequencies, F1 and F1+F2, aresent by the transmitter after being generated by mixing using oscillatorOsc. The two frequencies are needed by the SAW transducer where they aremixed yielding F2 which is modulated by the SAW and contains theinformation. Frequency (F1+F2) is sent only during the burst time whilefrequency F1 remains on until the signal F2 returns from the SAW. Thissignal is used for mixing. The signal returned from the SAW transducerto the interrogator is F1+F2 where F2 has been modulated by the SAWtransducer. It is expected that the mixing operations will result inabout 12 db loss in signal strength.

As discussed, theoretically a SAW can be used for any sensing functionprovided the surface across which the acoustic wave travels can bemodified in terms of its length, mass, elastic properties or anyproperty that affects the travel distance, speed, amplitude or dampingof the surface wave. Thus, gases and vapors can be sensed through theplacement of a layer on the SAW that absorbs the gas or vapor, forexample (a chemical sensor or electronic nose). Similarly, a radiationsensor can result through the placement of a radiation sensitive coatingon the surface of the SAW.

Normally, a SAW device is interrogated with a constant amplitude andfrequency RF pulse. This need not be the case and a modulated pulse canalso be used. If for example a pseudorandom or code modulation is used,then a SAW interrogator can distinguish its communication from that ofanother vehicle that may be in the vicinity. This doesn't totally solvethe problem of interrogating a tire that is on an adjacent vehicle butit does solve the problem of the interrogator being confused by thetransmission from another interrogator. This confusion can also bepartially solved if the interrogator only listens for a return signalbased on when it expects that signal to be present based on when it sentthe signal. That expectation can be based on the physical location ofthe tire relative to the interrogator which is unlikely to come from atire on an adjacent vehicle which only momentarily could be at anappropriate distance from the interrogator. The interrogator would ofcourse need to have correlation software in order to be able todifferentiate the relevant signals. The correlation technique alsopermits the interrogator to separate the desired signals from noisethereby improving the sensitivity of the correlator. An alternateapproach as discussed elsewhere herein is to combine a SAW sensor withan RFID switch where the switch is programmed to open or close based onthe receipt of the proper identification code.

As discussed elsewhere herein, the particular tire that is sending asignal can be determined if multiple antennas, such as three, eachreceive the signal. For a 500 MHz signal, for example, the wave lengthis about 60 cm. If the distance from a tire transmitter to each of threeantennas is on the order of one meter, then the relative distance fromeach antenna to the transmitter can be determined to within a fewcentimeters and thus the location of the transmitter can be found bytriangulation. If that location is not a possible location for a tiretransmitter, then the data can be ignored thus solving the problem of atransmitter from an adjacent vehicle being read by the wrong vehicleinterrogator. This will be discussed in more detail below with regard tosolving the problem of a truck having 18 tires that all need to bemonitored. Note also, each antenna can have associated with it somesimple circuitry that permits it to receive a signal, amplify it, changeits frequency and retransmit it either through a wire of through the airto the interrogator thus eliminating the need for long and expensivecoax cables.

U.S. Pat. No. 6,622,567 describes a peak strain RFID technology baseddevice with the novelty being the use of a mechanical device thatrecords the peak strain experienced by the device. Like the system ofthe invention herein, the system does not require a battery and receivesits power from the RFID circuit. The invention described herein includesthe use of RFID based sensors either in the peak strain mode or in thepreferred continuous strain mode. This invention is not limited tomeasuring strain as SAW and RFID based sensors can be used for measuringmany other parameters including chemical vapor concentration,temperature, acceleration, angular velocity etc.

A key aspect of at least one of the inventions disclosed herein is theuse of an interrogator to wirelessly interrogate multiple sensingdevices thereby reducing the cost of the system since such sensors arein general inexpensive compared to the interrogator. The sensing devicesare preferably based of SAW and/or RFID technologies although othertechnologies are applicable.

1.3.1 Antenna Considerations

Antennas are a very important aspect to SAW and RFID wireless devicessuch as can be used in tire monitors, seat monitors, weight sensors,child seat monitors, fluid level sensors and similar devices or sensorswhich monitor, detect, measure, determine or derive physical propertiesor characteristics of a component in or on the vehicle or of an areanear the vehicle, as disclosed in the current assignee's patents andpending patent applications. In many cases, the location of a SAW orRFID device needs to be determined such as when a device is used tolocate the position of a movable item in or on a vehicle such as a seat.In other cases, the particular device from a plurality of similardevices, such as a tire pressure and/or temperature monitor that isreporting, needs to be identified. Thus, a combination of antennas canbe used and the time or arrival, angle of arrival, multipath signatureor similar method used to identify the reporting device. One preferredmethod is derived from the theory of smart antennas whereby the signalsfrom multiple antennas are combined to improve the signal-to-noise ratioof the incoming or outgoing signal in the presence of multipath effects,for example.

Additionally, since the signal level from a SAW or RFID device isfrequently low, various techniques can be used to improve thesignal-to-noise ratio as described below. Finally, at the frequenciesfrequently used such as 433 MHz, the antennas can become large andmethods are needed to reduce their size. These and other antennaconsiderations that can be used to improve the operation of SAW, RFIDand similar wireless devices are described below.

1.3.1.1 Tire Information Determination

One method of maintaining a single central antenna assembly whileinterrogating all four tires on a conventional automobile, isillustrated in FIGS. 20A and 20B. An additional antenna can be locatednear the spare tire, which is not shown. It should be noted that thesystem described below is equally applicable for vehicles with more thanfour tires such as trucks.

A vehicle body is illustrated as 620 having four tires 621 and acentrally mounted four element, switchable directional antenna array622. The four beams are shown schematically as 623 with an inactivatedbeam as 624 and the activated beam as 625. The road surface 626 supportsthe vehicle. An electronic control circuit, not shown, which may resideinside the antenna array housing 622 or elsewhere, alternately switcheseach of the four antennas of the array 622 which then sequentially, orin some other pattern, send RF signals to each of the four tires 621 andwait for the response from the RFID, SAW or similar tire pressure,temperature, ID, acceleration and/or other property monitor arranged inconnection with or associated with the tire 621. This represents a timedomain multiple access system.

The interrogator makes sequential interrogation of wheels as follows:

Stage 1. Interrogator radiates 8 RF pulses via the first RF portdirected to the 1st wheel.

-   -   Pulse duration is about 0.8 μs.    -   Pulse repetition period is about 40 μs.    -   Pulse amplitude is about 8 V (peak to peak)    -   Carrier frequency is about 426.00 MHz.    -   (Of course, between adjacent pulses receiver opens its input and        receives four-pulses echoes from transponder located in the        first wheel).    -   Then, during a time of about 8 ms internal micro controller        processes and stores received data.    -   Total duration of this stage is 32 μs+8 ms=8.032 ms.        Stage 2,3,4. Interrogator repeats operations as on stage 1 for        2^(nd), 3^(rd) and 4^(th) wheel sequentially via appropriate RF        ports.        Stage 5. Interrogator stops radiating RF pulses and transfers        data stored during stages 1-4 to the external PC for final        processing and displaying. Then it returns to stage 1. The time        interval for data transfer equals about 35 ms.    -   Some notes relative to FCC Regulations:    -   The total duration of interrogation cycle of four wheels is        8.032 ms*4+35 ms=67.12 ms.    -   During this time, interrogator radiates 8*4=32 pulses, each of        0.8 μs duration.    -   Thus, average period of pulse repetition is        67.12 ms/32=2.09 ms=2090 μs    -   Assuming that duration of the interrogation pulse is 0.8 μs as        mentioned, an average repetition rate is obtained        0.8 μs/2090 μs=0.38*10⁻³    -   Finally, the radiated pulse power is        Pp=(4 V)²/(2*50 Ohm)=0.16 W    -   and the average radiated power is        Pave=0.16*0.38*10⁻³=0.42*10⁻³W, or 0.42 mW

In another application, the antennas of the array 622 transmit the RFsignals simultaneously and space the returns through the use of a delayline in the circuitry from each antenna so that each return is spaced intime in a known manner without requiring that the antennas be switched.Another method is to offset the antenna array, as illustrated in FIG.21, so that the returns naturally are spaced in time due to thedifferent distances from the tires 621 to the antennas of the array 622.In this case, each signal will return with a different phase and can beseparated by this difference in phase using methods known to those inthe art.

In another application, not shown, two wide angle antennas can be usedsuch that each receives any four signals but each antenna receives eachsignal at a slightly different time and different amplitude permittingeach signal to be separated by looking at the return from both antennassince, each signal will be received differently based on its angle ofarrival.

Additionally, each SAW or RFID device can be designed to operate on aslightly different frequency and the antennas of the array 622 can bedesigned to send a chirp signal and the returned signals will then beseparated in frequency, permitting the four signals to be separated.Alternately, the four antennas of the array 622 can each transmit anidentification signal to permit separation. This identification can be anumerical number or the length of the SAW substrate, for example, can berandom so that each property monitor has a slightly different delaybuilt in which permits signal separation. The identification number canbe easily achieved in RFID systems and, with some difficulty and addedexpense, in SAW systems. Other methods of separating the signals fromeach of the tires 621 will now be apparent to those skilled in the art.One preferred method in particular will be discussed below and makes useof an RFID switch.

There are two parameters of SAW system, which has led to the choice of afour echo pulse system:

-   -   ITU frequency rules require that the radiated spectrum width be        reduced to:        Δφ≦1.75 MHz (in ISM band, F=433.92 MHz);    -   The range of temperature measurement should be from −40 F up to        +260 F.

Therefore, burst (request) pulse duration should be not less than 0.6microseconds (see FIG. 22).τ_(bur.)=1/Δφ≧0.6 μs

This burst pulse travels to a SAW sensor and then it is returned by theSAW to the interrogator. The sensor's antenna, interdigital transducer(IDT), reflector and the interrogator are subsystems with a restrictedfrequency pass band. Therefore, an efficient pass band of all thesubsystems H(f)_(Σ) will be defined as product of the partial frequencycharacteristic of all components:H(f)_(Σ) =H(f)₁ *H(f)₂ * . . . H(f)i

On the other hand, the frequency H(φ)_(Σ) and a time I(τ)_(Σ) responseof any system are interlinked to each other by Fourier's transform.Therefore, the shape and duration (τ_(echo puls)) an echo signal oninput to the quadrature demodulator will differ from an interrogationpulse (see FIG. 23).

In other words, duration an echo signal on input to the quadraturedemodulator is defined as mathematical convolution of a burst signalτ_(bur.) and the total impulse response of the system I(τ)_(Σ).τ_(echo)=τ_(bur.) {circle around (x)}I(τ)_(Σ)

The task is to determine maximum pulse duration on input to thequadrature demodulator τ_(echo) under a burst pulse duration τ_(bur) of0.6 microseconds. It is necessary to consider in time all echo signals.In addition, it is necessary to take into account the following:

-   -   each subsequent echo signal should not begin earlier than the        completion of the previous echo pulse. Otherwise, the signals        will interfere with each other, and measurement will not be        correct;    -   for normal operation of available microcircuits, it is necessary        that the signal has a flat apex with a duration not less than        0.25 microseconds (τ_(meg)=t3−t2, see FIG. 23). The signal's        phase will be constant only on this segment;    -   the total sensor's pass band (considering double transit IDT and        its antenna as a reflector) constitutes 10 MHz;    -   the total pass band of the interrogator constitutes no more than        4 MHz.

Conducting the corresponding calculations yields the determination thatduration of impulse front (t2−t1=t4−t3, see FIG. 23) constitutes about0.35 microseconds. Therefore, total duration of one echo pulse is notless than:τ_(echo.)=(t2−t1)+τ_(meg.)+(t4−t3)=0.35+0.25+0.35=0.95 μs

Hence, the arrival time of each following echo pulse should be notearlier than 1.0 microsecond (see FIG. 24). This conclusion is veryimportant.

In Appendix 1 of the '139 application, it is shown that for correcttemperature measuring in the required band it is necessary to meet thefollowing conditions:(T2−T1)=1/(72*10−6/° K*(125° C.−(−40° C.))*434.92*106)=194 ns

This condition is outrageous. If to execute ITU frequency rules, theband of correct temperature measuring will be reduced five times:(125° C.−(−40° C.)*194 ns)/1000 ns=32° C.=58° F.

This is the main reason that it is necessary to add the fourth echopulse in a sensor (see FIG. 24). The principle purpose of the fourthecho pulse is to make the temperature measurement unambiguous in a wideinterval of temperatures when a longer interrogation pulse is used (therespective time intervals between the sensor's echo pulses are alsolonger). A mathematical model of the processing of a four-pulse echothat explains these statements is presented in Appendix 3 of the '139application.

The duration of the interrogation pulse and the time positions of thefour pulses are calculated as:T1>4*τ_(echo)=4.00 μsT2=T1+τ_(echo)=5.00 μsT3=T2+τ_(echo)=6.00 μsT4=T3+τ_(echo)+0.08 μs=7.08 μs

The sensor's design with four pulses is exhibited in FIG. 25 and FIG.26.

τ_(bur) 0.60 μs T1 4.00 μs T2 5.00 μs T3 6.00 μs T4 7.08 μs

The reason that such a design was selected is that this design providesthree important conditions:

1. It has the minimum RF signal propagation loss. Both SAW waves use formeasuring (which are propagated to the left and to the right from IDT).

2. All parasitic echo signals (signals of multiple transits) areeliminated after the fourth pulse. For example, the pulse is excited bythe IDT, then it is reflected from a reflector No1 and returns to theIDT. The pulse for the second time is re-emitted and it passes thesecond time on the same trajectory. The total time delay will be 8.0microseconds in this case.

3. It has the minimum length.

FIGS. 25-27 illustrate paths taken by various surface waves on a tiretemperature and pressure monitoring device of one or more of theinventions disclosed herein. The pulse from the interrogator is receivedby the antenna 634 which excited a wave in the SAW substrate 637 by wayof the interdigital transducer (IDT) 633. The pulse travels in twodirections and reflects off of reflectors 631, 632, 635 and 636. Thereflected pulses return to the IDT 633 and are re-radiated from theantenna 634 back to the interrogator. The pressure in the pressurecapsule causes the micro-membrane 638 to deflect causing the membrane tostrain in the SAW through the point of application of the force 639.

The IDT 633, reflectors 632 and 631 are rigidly fastened to a basepackage. Reflectors 635 and 636 are disposed on a portion of thesubstrate that moves under the action of changes in pressure. Therefore,it is important that magnitudes of phase shift of pulses No2 and No4were equal for a particular pressure.

For this purpose, the point of application of the force (caused bypressure) has been arranged between reflector 635 and the IDT 633, as itis exhibited in FIG. 27. Phase shifts of echo pulses No2 and No4 varyequally with changes in pressure. The area of strain is equal for echopulses No2 and No4. Phase shifts of echo pulses No1 and No4 do not varywith pressure.

The phase shifts of all four echo pulses vary under temperature changes(proportionally to each time delay). All necessary computing of thetemperature and pressure can be executed without difficulties in thiscase only.

This is taken into account in a math model, which is presented below.

Although the discussion herein concerns the determination of tireinformation, the same system can be used to determine the location ofseats, the location of child seats when equipped with sensors,information about the presence of object or chemicals in vehicularcompartments and the like.

1.3.1.2 Smart Antennas

Some of the shortcomings in today's wireless products can be overcome byusing smart antenna technology. A smart antenna is a multi-elementantenna that significantly improves reception by intelligently combiningthe signals received at each antenna element and adjusting the antennacharacteristics to optimize performance as the transmitter or receivermoves and the environment changes.

Smart antennas can suppress interfering signals, combat signal fadingand increase signal range thereby increasing the performance andcapacity of wireless systems.

A method of separating signals from multiple tires, for example, is touse a smart antenna such as that manufactured by Motia. This particularMotia device is designed to operate at 433 MHz and to mitigate multipathsignals at that frequency. The signals returning to the antennas fromtires, for example, contain some multipath effects that, especially ifthe antennas are offset somewhat from the vehicle center, are differentfor each wheel. Since the adaptive formula will differ for each wheel,the signals can be separated (see “enhancing 802.11 WLANs through SmartAntennas”, January 2004 available at motia.com). The following is takenfrom that paper.

“Antenna arrays can provide gain, combat multipath fading, and suppressinterfering signals, thereby increasing both the performance andcapacity of wireless systems. Smart antennas have been implemented in awide variety of wireless systems, where they have been demonstrated toprovide a large performance improvement. However, the various types ofspatial processing techniques have different advantages anddisadvantages in each type of system.”

“This strategy permits the seamless integration of smart antennatechnology with today's legacy WLAN chipset architecture. Since the802.11 system uses time division duplexing (the same frequency is usedfor transmit and receive), smart antennas can be used for both transmitand receive, providing a gain on both uplink and downlink, using smartantennas on either the client or access point alone. Results show a 13dB gain with a four element smart antenna over a single antenna systemwith the smart antenna on one side only, and an 18 dB gain with thesmart antenna on both the client and access point. Thus, this“plug-and-play” adaptive array technology can provide greater range,average data rate increases per user, and better overall coverage.

“In the multibeam or phased array antenna, a beamformer forms severalnarrow beams, and a beam selector chooses the beam for reception thathas the largest signal power. In the adaptive array, the signal isreceived by several antenna elements, each with similar antennapatterns, and the received signals are weighted and combined to form theoutput signal. The multibeam antenna is simpler to implement as thebeamformer is fixed, with the beam selection only needed every fewseconds for user movement, while the adaptive array must calculate thecomplex beamforming weights at least an order of magnitude faster thanthe fading rate, which can be several Hertz for pedestrian users.”

“Finally, there is pattern diversity, the use of antenna elements withdifferent patterns. The combination of these types of diversity permitsthe use of a large number of antennas even in a small form factor, suchas a PCMCIA card or handset, with near ideal performance.”

Through its adaptive beamforming technology, Motia has developedcost-effective smart antenna appliqués that vastly improve wirelessperformance in a wide variety of wireless applications including Wi-Fithat can be incorporated into wireless systems without majormodifications to existing products. Although the Motia chipset has beenapplied to several communication applications, it has yet to be appliedto the monitoring applications as disclosed in the current assignee'spatents and pending patent applications, and in particular vehicularmonitoring applications such as tire monitoring.

The smart antenna works by determining a set of factors or weights thatare used to operate on the magnitude and/or phase of the signals fromeach antenna before the signals are combined. However, since thegeometry of a vehicle tire relative to the centralized antenna arraydoes not change much as the tire rotates, but is different for eachwheel, the weights themselves contain the information as to which tiresignal is being received. In fact, the weights can be chosen to optimizesignal transmission from a particular tire thus providing a method ofselectively interrogating each tire at the maximum antenna gain.

1.3.1.3 Distributed Load Monopole

Recent antenna developments in the physics department at the Universityof Rhode Island have resulted in a new antenna technology. The antennasdeveloped called DLM's (Distributed loaded monopole) are smallefficient, wide bandwidth antennas. The simple design exhibits 50-ohmimpedance and is easy to implement. They require only a direct feed froma coax cable and require no elaborate matching networks.

The prime advantage to this technology is a substantial reduction of thesize of an antenna. Typically, the DLM antenna is about ⅓ the size of anormal dipole with only minor loss in efficiency. This is especiallyimportant for vehicle applications where space is always at a premium.Such antennas can be used for a variety of vehicle radar andcommunication applications as well for the monitoring of RFID, SAW andsimilar devices on a vehicle and especially for tire pressure,temperature, and/or acceleration monitoring as well as other monitoringpurposes. Such applications have not previously been disclosed.

Although the DLM is being applied to several communication applications,it has yet to be applied to the monitoring applications as disclosed inthe current assignee's patents and pending patent applications. Theantenna gain that results and the ability to pack several antennas intoa small package are attractive features of this technology.

1.3.1.4 Plasma Antenna

The following disclosure was taken from “Markland Technologies—GasPlasma”: (www.marklandtech.com)

“Plasma antenna technology employs ionized gas enclosed in a tube (orother enclosure) as the conducting element of an antenna. This is afundamental change from traditional antenna design that generallyemploys solid metal wires as the conducting element. Ionized gas is anefficient conducting element with a number of important advantages.Since the gas is ionized only for the time of transmission or reception,“ringing” and associated effects of solid wire antenna design areeliminated. The design allows for extremely short pulses, important tomany forms of digital communication and radars. The design furtherprovides the opportunity to construct an antenna that can be compact anddynamically reconfigured for frequency, direction, bandwidth, gain andbeamwidth. Plasma antenna technology will enable antennas to be designedthat are efficient, low in weight and smaller in size than traditionalsolid wire antennas.”

“When gas is electrically charged, or ionized to a plasma state itbecomes conductive, allowing radio frequency (RF) signals to betransmitted or received. We employ ionized gas enclosed in a tube as theconducting element of an antenna. When the gas is not ionized, theantenna element ceases to exist. This is a fundamental change fromtraditional antenna design that generally employs solid metal wires asthe conducting element. We believe our plasma antenna offers numerousadvantages including stealth for military applications and higherdigital performance in commercial applications. We also believe ourtechnology can compete in many metal antenna applications.”

“Initial studies have concluded that a plasma antenna's performance isequal to a copper wire antenna in every respect. Plasma antennas can beused for any transmission and/or modulation technique: continuous wave(CW), phase modulation, impulse, AM, FM, chirp, spread spectrum or otherdigital techniques. And the plasma antenna can be used over a largefrequency range up to 20 GHz and employ a wide variety of gases (forexample neon, argon, helium, krypton, mercury vapor and xenon). The sameis true as to its value as a receive antenna.”

“Plasma antenna technology has the following additional attributes:

-   -   No antenna ringing provides an improved signal to noise ratio        and reduces multipath signal distortion.    -   Reduced radar cross section provides stealth due to the        non-metallic elements.    -   Changes in the ion density can result in instantaneous changes        in bandwidth over wide dynamic ranges.    -   After the gas is ionized, the plasma antenna has virtually no        noise floor.    -   While in operation, a plasma antenna with a low ionization level        can be decoupled from an adjacent high-frequency transmitter.    -   A circular scan can be performed electronically with no moving        parts at a higher speed than traditional mechanical antenna        structures.    -   It has been mathematically illustrated that by selecting the        gases and changing ion density that the electrical aperture (or        apparent footprint) of a plasma antenna can be made to perform        on par with a metal counterpart having a larger physical size.    -   Our plasma antenna can transmit and receive from the same        aperture provided the frequencies are widely separated.    -   Plasma resonance, impedance and electron charge density are all        dynamically reconfigurable. Ionized gas antenna elements can be        constructed and configured into an array that is dynamically        reconfigurable for frequency, beamwidth, power, gain,        polarization and directionality—on the fly.    -   A single dynamic antenna structure can use time multiplexing so        that many RF subsystems can share one antenna resource reducing        the number and size of antenna structures.”

Several of the characteristics discussed above are of particularusefulness for several of the inventions herein including the absence ofringing, the ability to turn the antenna off after transmission and thenimmediately back on for reception, the ability to send very shortpulses, the ability to alter the directionality of the antenna and tosweep thereby allowing one antenna to service multiple devices such astires and to know which tire is responding. Additional advantagesinclude, smaller size, the ability to work with chirp, spread spectrumand other digital technologies, improved signal to noise ratio, widedynamic range, circular scanning without moving parts, and antennasharing over differing frequencies, among others.

Some of the applications disclosed herein can use ultra widebandtransceivers. UWB transceivers radiate most of the energy with itsfrequency centered on the physical length of the antenna. With the UWBconnected to a plasma antenna, the center frequency of the UWBtransceiver could be hopped or swept simultaneously.

A plasma antenna can solve the problem of multiple antennas by changingits electrical characteristic to match the function required—Time domainmultiplexed. It can be used for high-gain antennas such as phase array,parabolic focus steering, log periodic, yogi, patch quadrafiler, etc.One antenna can be used for GPS, ad-hoc (such as car-to-car)communication, collision avoidance, back up sensing, cruse control,radar, toll identification and data communications.

Although the plasma antennas are being applied to several communicationapplications, they have yet to be applied to the monitoring applicationsas disclosed herein. The many advantages that result and the ability topack several antenna functions into a small package are attractivefeatures of this technology. Patents and applications that discussplasma antennas include: U.S. Pat. No. 6,710,746, US20030160742 andUS20040130497.

1.3.1.5 Dielectric Antenna

A great deal of work is underway to make antennas from dielectricmaterials. In one case, the electric field that impinges on thedielectric is used to modulate a transverse electric light beam. Inanother case, the reduction of the speed of electro magnetic waves dueto the dielectric constant is used to reduce the size of the antenna. Itcan be expected that developments in this area will affect the antennasused in cell phones as well as in RFID and SAW-based communicationdevices in the future. Thus, dielectric antennas can be advantageouslyused with some of the inventions disclosed herein.

1.3.1.6 Nanotube Antenna

Antennas made from carbon nanotubes are beginning to show promise ofincreasing the sensitivity of antennas and thus increasing the range forcommunication devices based on RFID, SAW or similar devices where thesignal strength frequently limits the range of such devices. The use ofthese antennas is therefore contemplated herein for use in tire monitorsand the other applications disclosed herein.

Combinations of the above antenna designs in many cases can benefit fromthe advantages of each type to add further improvements to the field.Thus the inventions herein are not limited to any one of the aboveconcepts nor is it limited to their use alone. Where feasible, allcombinations are contemplated herein.

1.3.1.7 Summary

A general system for obtaining information about a vehicle or acomponent thereof or therein is illustrated in FIG. 20C and includesmultiple sensors 627 which may be arranged at specific locations on thevehicle, on specific components of the vehicle, on objects temporarilyplaced in the vehicle such as child seats, or on or in any other objectin or on the vehicle or in its vicinity about which information isdesired. The sensors 627 may be SAW or RFID sensors or other sensorswhich generate a return signal upon the detection of a transmitted radiofrequency signal. A multi-element antenna array 622 is mounted on thevehicle, in either a central location as shown in FIG. 20A or in anoffset location as shown in FIG. 21, to provide the radio frequencysignals which cause the sensors 627 to generate the return signals.

A control system 628 is coupled to the antenna array 622 and controlsthe antennas in the array 622 to be operative as necessary to enablereception of return signals from the sensors 627. There are several waysfor the control system 628 to control the array 622, including to causethe antennas to be alternately switched on in order to sequentiallytransmit the RF signals therefrom and receive the return signals fromthe sensors 627 and to cause the antennas to transmit the RF signalssimultaneously and space the return signals from the sensors 627 via adelay line in circuitry from each antennas such that each return signalis spaced in time in a known manner without requiring switching of theantennas. The control system can also be used to control a smart antennaarray.

The control system 628 also processes the return signals to provideinformation about the vehicle or the component. The processing of thereturn signals can be any known processing including the use of patternrecognition techniques, neural networks, fuzzy systems and the like.

The antenna array 622 and control system 628 can be housed in a commonantenna array housing 630.

Once the information about the vehicle or the component is known, it isdirected to a display/telematics/adjustment unit 629 where theinformation can be displayed on a display 629 to the driver, sent to aremote location for analysis via a telematics unit 629 and/or used tocontrol or adjust a component on, in or near the vehicle. Althoughseveral of the figures illustrate applications of these technologies totire monitoring, it is intended that the principles and devicesdisclosed can be applied to the monitoring of a wide variety ofcomponents on and off a vehicle.

1.4 Tire Monitoring

The tire monitoring systems of some of the inventions herein comprisesat least three separate systems corresponding to three stages of productevolution. Generation 1 is a tire valve cap that provides information asto the pressure within the tire as described below. Generation 2requires the replacement of the tire valve stem, or the addition of anew stem-like device, with a new valve stem that also measurestemperature and pressure within the tire or it may be a device thatattaches to the vehicle wheel rim. Generation 3 is a product that isattached to the inside of the tire adjacent the tread and provides ameasure of the diameter of the footprint between the tire and the road,the tire pressure and temperature, indications of tire wear and, in somecases, the coefficient of friction between the tire and the road.

As discussed above, SAW technology permits the measurement of manyphysical and chemical parameters without the requirement of local poweror energy. Rather, the energy to run devices can be obtained from radiofrequency electromagnetic waves. These waves excite an antenna that iscoupled to the SAW device. Through various devices, the properties ofthe acoustic waves on the surface of the SAW device are modified as afunction of the variable to be measured. The SAW device belongs to thefield of microelectromechanical systems (MEMS) and can be produced inhigh-volume at low cost.

For the Generation 1 system, a valve cap contains a SAW material at theend of the valve cap, which may be polymer covered. This device sensesthe absolute pressure in the valve cap. Upon attaching the valve cap tothe valve stem, a depressing member gradually depresses the valvepermitting the air pressure inside the tire to communicate with a smallvolume inside the valve cap. As the valve cap is screwed onto the valvestem, a seal prevents the escape of air to the atmosphere. The SAWdevice is electrically connected to the valve cap, which is alsoelectrically connected to the valve stem that can act as an antenna fortransmitting and receiving radio frequency waves. An interrogatorlocated in the vicinity of the tire periodically transmits radio wavesthat power the SAW device, the actual distance between the interrogatorand the device depending on the relative orientation of the antennas andother factors. The SAW device measures the absolute pressure in thevalve cap that is equal to the pressure in the tire.

The Generation 2 system permits the measurement of both the tirepressure and tire temperature. In this case, the tire valve stem can beremoved and replaced with a new tire valve stem that contains a SAWdevice attached at the bottom of the valve stem. This device preferablycontains two SAW devices, one for measuring temperature and the secondfor measuring pressure through a novel technology discussed below. Thissecond generation device therefore permits the measurement of both thepressure and the temperature inside the tire. Alternately, this devicecan be mounted inside the tire, attached to the rim or attached toanother suitable location. An external pressure sensor is mounted in theinterrogator to measure the pressure of the atmosphere to compensate foraltitude and/or barometric changes.

The Generation 3 device can contain a pressure and temperature sensor,as in the case of the Generation 2 device, but additionally contains oneor more accelerometers which measure at least one component of theacceleration of the vehicle tire tread adjacent the device. Thisacceleration varies in a known manner as the device travels in anapproximate circle attached to the wheel. This device is capable ofdetermining when the tread adjacent the device is in contact with roadsurface. In some cases, it is also able to measure the coefficient offriction between the tire and the road surface. In this manner, it iscapable of measuring the length of time that this tread portion is incontact with the road and thereby can provide a measure of the diameteror circumferential length of the tire footprint on the road. A technicaldiscussion of the operating principle of a tire inflation and loaddetector based on flat area detection follows:

When tires are inflated and not in contact with the ground, the internalpressure is balanced by the circumferential tension in the fibers of theshell. Static equilibrium demands that tension is equal to the radius ofcurvature multiplied by the difference between the internal and theexternal gas pressure. Tires support the weight of the automobile bychanging the curvature of the part of the shell that touches the ground.The relation mentioned above is still valid. In the part of the shellthat gets flattened, the radius of curvature increases while the tensionin the tire structure stays the same. Therefore, the difference betweenthe external and internal pressures becomes small to compensate for thegrowth of the radius. If the shell were perfectly flexible, the tirecontact with the ground would develop into a flat spot with an areaequal to the load divided by the pressure.

A tire operating at correct values of load and pressure has a precisesignature in terms of variation of the radius of curvature in the loadedzone. More flattening indicates under-inflation or over-loading, whileless flattening indicates over-inflation or under-loading. Note thattire loading has essentially no effect on internal pressure.

From the above, one can conclude that monitoring the curvature of thetire as it rotates can provide a good indication of its operationalstate. A sensor mounted inside the tire at its largest diameter canaccomplish this measurement. Preferably, the sensor would measuremechanical strain. However, a sensor measuring acceleration in any oneaxis, preferably the radial axis, could also serve the purpose.

In the case of the strain measurement, the sensor would indicate aconstant strain as it spans the arc over which the tire is not incontact with the ground and a pattern of increased stretch during thetime when the sensor spans an arc in close proximity with the ground. Asimple ratio of the times of duration of these two states would providea good indication of inflation, but more complex algorithms could beemployed where the values and the shape of the period of increasedstrain are utilized.

As an indicator of tire health, the measurement of strain on the largestinside diameter of the tire is believed to be superior to themeasurement of stress, such as inflation pressure, because, the tirecould be deforming, as it ages or otherwise progresses toward failure,without any changes in inflation pressure. Radial strain could also bemeasured on the inside of the tire sidewall thus indicating the degreeof flexure that the tire undergoes.

The accelerometer approach has the advantage of giving a signature fromwhich a harmonic analysis of once-per-revolution disturbances couldindicate developing problems such as hernias, flat spots, loss of partof the tread, sticking of foreign bodies to the tread, etc.

As a bonus, both of the above-mentioned sensors (strain andacceleration) give clear once-per-revolution signals for each tire thatcould be used as input for speedometers, odometers, differential slipindicators, tire wear indicators, etc.

Tires can fail for a variety of reasons including low pressure, hightemperature, delamination of the tread, excessive flexing of thesidewall, and wear (see, e.g., Summary Root Cause AnalysisBridgestone/Firestone, Inc.”http://www.bridgestone-firestone.com/homeimgs/rootcause.htm, PrintedMarch, 2001). Most tire failures can be predicted based on tire pressurealone and the TREAD Act thus addresses the monitoring of tire pressure.However, some failures, such as the Firestone tire failures, can resultfrom substandard materials especially those that are in contact with asteel-reinforcing belt. If the rubber adjacent the steel belt begins tomove relative to the belt, then heat will be generated and thetemperature of the tire will rise until the tire fails catastrophically.This can happen even in properly inflated tires.

Finally, tires can fail due to excessive vehicle loading and excessivesidewall flexing even if the tire is properly inflated. This can happenif the vehicle is overloaded or if the wrong size tire has been mountedon the vehicle. In most cases, the tire temperature will rise as aresult of this additional flexing, however, this is not always the case,and it may even occur too late. Therefore, the device which measures thediameter of the tire footprint on the road is a superior method ofmeasuring excessive loading of the tire.

Generation 1 devices monitor pressure only while Generation 2 devicesalso monitor the temperature and therefore will provide a warning ofimminent tire failure more often than if pressure alone is monitored.Generation 3 devices will provide an indication that the vehicle isoverloaded before either a pressure or temperature monitoring system canrespond. The Generation 3 system can also be augmented to measure thevibration signature of the tire and thereby detect when a tire has wornto the point that the steel belt is contacting the road. In this manner,the Generation 3 system also provides an indication of a worn out tireand, as will be discussed below, an indication of the road coefficientof friction.

Each of these devices communicates to an interrogator with pressure,temperature, and acceleration as appropriate. In none of thesegenerational devices is a battery mounted within the vehicle tirerequired, although in some cases an energy generator can be used. Insome cases, the SAW or RFID devices will optionally provide anidentification number corresponding to the device to permit theinterrogator to separate one tire from another.

Key advantages of the tire monitoring system disclosed herein over mostof the currently known prior art are:

-   -   very small size and weight eliminating the need for wheel        counterbalance,    -   cost competitive for tire monitoring alone and cost advantage        for combined systems,    -   high update rate,    -   self-diagnostic,    -   automatic wheel identification,    -   no batteries required—powerless, and

no wires required—wireless.

The monitoring of temperature and or pressure of a tire can take placeinfrequently. It can be adequate to check the pressure and temperatureof vehicle tires once every ten seconds to once per minute. To utilizethe centralized interrogator of this invention, the tire monitoringsystem would preferably use SAW technology and the device could belocated in the valve stem, wheel, tire side wall, tire tread, or otherappropriate location with access to the internal tire pressure of thetires. A preferred system is based on a SAW technology discussed above.

At periodic intervals, such as once every minute, the interrogator sendsa radio frequency signal at a frequency such as 905 MHz to which thetire monitor sensors have been sensitized. When receiving this signal,the tire monitor sensors (of which there are five in a typicalconfiguration) respond with a signal providing an optionalidentification number, temperature, pressure and acceleration data whereappropriate. In one implementation, the interrogator would use multiple,typically two or four, antennas which are spaced apart. By comparing thetime of the returned signals from the tires to the antennas, or by usingsmart antenna techniques, the location of each of the senders (thetires) can be approximately determined as discussed in more detailabove. That is, the antennas can be so located that each tire is adifferent distance from each antenna and by comparing the return time ofthe signals sensed by the antennas, the location of each tire can bedetermined and associated with the returned information. If at leastthree antennas are used, then returns from adjacent vehicles can beeliminated. Alternately, a smart antenna array such as manufactured byMotia can be used.

An illustration of this principle applied to an 18 wheeler truck vehicleis shown generally at 610 in FIGS. 28A and 28B. Each of the vehiclewheels is represented by a rectangle 617. In FIG. 28A, the antennas 611and 612 are placed near to the tires due to the short transmission rangeof typical unboosted SAW tire monitor systems. In FIG. 28B, transmitterssuch as conventional battery operated systems or boosted SAW systems,for example, allow a reduction in the number of antennas and theirplacement in a more central location such as antennas 614, 615 and 616.In FIG. 28A, antennas 611, 612 transmit an interrogation signalgenerated in the interrogator 613 to tires in their vicinity. Antennas611 and 612 then receive the retransmitted signals and based on the timeof arrival or the phase differences between the arriving signals, thedistance or direction from the antennas to the transmitters can bedetermined by triangulation or based on the intersection of thecalculated vectors, the location of the transmitter can be determined bythose skilled in the art. For example, if there is a smaller phasedifference between the received signals at antennas 611 and 612, thenthe transmitter will be inboard and if the phase difference is larger,then the transmitter will be an outboard tire. The exact placement ofeach antenna 611, 612 can be determined by analysis or byexperimentation to optimize the system. The signals received by theantennas 611, 612 can be transmitted as received to the interrogator 613by wires (not shown) or, at the other extreme, each antenna 611, 612 canhave associated circuitry to process the signal to change its frequencyand/or amplify the received signal and retransmit it by wires orwirelessly to the transmitter. Various combinations of features can alsobe used. If processing circuitry is present, then each antenna with suchcircuitry would need a power source which can be supplied by theinterrogator or by another power-supply method. If supplied by theinterrogator, power can be supplied using the same cabling as is used tosend the interrogating pulse which may be a coax cable. Since the powercan be supplied as DC, it can be easily separated from the RF signal.Naturally, this system can be used with all types of tire monitors andis not limited to SAW type devices. Other methods exist to transmit datafrom the antennas including a vehicle bus or a fiber optic line or bus.

In FIG. 28B, the transmitting antenna 615 is used for 16 of the wheelsand receiving antennas 614, and optionally antenna 615, are used todetermine receipt of the TPM signals and determine the transmitting tireas described above. However, since the range of the tire monitors isgreater in this case, the antennas 614, 615 can be placed in a morecentralized location thereby reducing the cost of the installation andimproving its reliability.

Other methods can also be used to permit tire differentiation includingCDMA and FDMA, for example, as discussed elsewhere herein. If, forexample, each device is tuned to a slightly different frequency or codeand this information is taught to the interrogator, then the receivingantenna system can be simplified.

An identification number can accompany each transmission from each tiresensor and can also be used to validate that the transmitting sensor isin fact located on the subject vehicle. In traffic situations, it ispossible to obtain a signal from the tire of an adjacent vehicle. Thiswould immediately show up as a return from more than five vehicle tiresand the system would recognize that a fault had occurred. The sixthreturn can be easily eliminated, however, since it could contain anidentification number that is different from those that have heretoforebeen returned frequently to the vehicle system or based on a comparisonof the signals sensed by the different antennas. Thus, when the vehicletire is changed or tires are rotated, the system will validate aparticular return signal as originating from the tire-monitoring sensorlocated on the subject vehicle.

This same concept is also applicable for other vehicle-mounted sensors.This permits a plug and play scenario whereby sensors can be added to,changed, or removed from a vehicle and the interrogation system willautomatically adjust. The system will know the type of sensor based onthe identification number, frequency, delay and/or its location on thevehicle. For example, a tire monitor could have an ID in a differentrange of identification numbers from a switch or weight-monitoringdevice. This also permits new kinds of sensors to be retroactivelyinstalled on a vehicle. If a totally new type of the sensor is mountedto the vehicle, the system software would have to be updated torecognize and know what to do with the information from the new sensortype. By this method, the configuration and quantity of sensing systemson a vehicle can be easily changed and the system interrogating thesesensors need only be updated with software upgrades which could occurautomatically, such as over the Internet and by any telematicscommunication channel including cellular and satellite.

Preferred tire-monitoring sensors for use with this invention use thesurface acoustic wave (SAW) technology. A radio frequency interrogatingsignal can be sent to all of the tire gages simultaneously and thereceived signal at each tire gage is sensed using an antenna. Theantenna is connected to the IDT transducer that converts the electricalwave to an acoustic wave that travels on the surface of a material suchas lithium niobate, or other piezoelectric material such as zinc oxide,Langasite™ or the polymer polyvinylidene fluoride (PVDF). During itstravel on the surface of the piezoelectric material, either the timedelay, resonant frequency, amplitude or phase of the signal (or evenpossibly combinations thereof) is modified based on the temperatureand/or pressure in the tire. This modified wave is sensed by one or moreIDT transducers and converted back to a radio frequency wave that isused to excite an antenna for re-broadcasting the wave back tointerrogator. The interrogator receives the wave at a time delay afterthe original transmission that is determined by the geometry of the SAWtransducer and decodes this signal to determine the temperature and/orpressure in the subject tire. By using slightly different geometries foreach of the tire monitors, slightly different delays can be achieved andrandomized so that the probability of two sensors having the same delayis small. The interrogator transfers the decoded information to acentral processor that determines whether the temperature and/orpressure of each of the tires exceed specifications. If so, a warninglight can be displayed informing the vehicle driver of the condition.Other notification devices such as a sound generator, alarm and the likecould also be used. In some cases, this random delay is all that isrequired to separate the five tire signals and to identify which tiresare on the vehicle and thus ignore responses from adjacent vehicles.

With an accelerometer mounted in the tire, as is the case for theGeneration 3 system, information is present to diagnose other tireproblems. For example, when the steel belt wears through the rubbertread, it will make a distinctive noise and create a distinctivevibration when it contacts the pavement. This can be sensed by a SAW orother technology accelerometer. The interpretation of various suchsignals can be done using neural network technology. Similar systems aredescribed more detail in U.S. Pat. No. 5,829,782. As the tread begins toseparate from the tire as in the Bridgestone cases, a distinctivevibration is created which can also be sensed by a tire-mountedaccelerometer.

As the tire rotates, stresses are created in the rubber tread surfacebetween the center of the footprint and the edges. If the coefficient offriction on the pavement is low, these stresses can cause the shape ofthe footprint to change. The Generation 3 system, which measures thecircumferential length of the footprint, can therefore also be used tomeasure the friction coefficient between the tire and the pavement.

Piezoelectric generators are another field in which SAW technology canbe applied and some of the inventions herein can comprise severalembodiments of SAW or other piezoelectric or other generators, asdiscussed extensively elsewhere herein.

An alternate approach for some applications, such as tire monitoring,where it is difficult to interrogate the SAW device as the wheel, andthus the antenna is rotating; the transmitting power can besignificantly increased if there is a source of energy inside the tire.Many systems now use a battery but this leads to problems related todisposal, having to periodically replace the battery and temperatureeffects. In some cases, the manufacturers recommend that the battery bereplaced as often as every 6 to 12 months. Batteries also sometimes failto function properly at cold temperatures and have their life reducedwhen operated at high temperatures. For these reasons, there is a beliefthat a tire monitoring system should obtain its power from some sourceexternal of the tire. Similar problems can be expected for otherapplications.

One novel solution to this problem is to use the flexing of the tireitself to generate electricity. If a thin film of PVDF is attached tothe tire inside and adjacent to the tread, then as the tire rotates thefilm will flex and generate electricity. This energy can then be storedon one or more capacitors and used to power the tire monitoringcircuitry. Also, since the amount of energy that is generated depends ofthe flexure of the tire, this generator can also be used to monitor thehealth of the tire in a similar manner as the Generation 3 accelerometersystem described above. Mention is made of using a bi-morph to generateenergy in a rotating tire in U.S. Pat. No. 5,987,980 without describinghow it is implemented other than to say that it is mounted to the sensorhousing and uses vibration. In particular, there is no mention ofattaching the bi-morph to the tread of the tire as disclosed herein.

As mentioned above, the transmissions from different SAW devices can betime-multiplexed by varying the delay time from device to device,frequency-multiplexed by varying the natural frequencies of the SAWdevices, code-multiplexed by varying the identification code of the SAWdevices or space-multiplexed by using multiple antennas. Additionally, acode operated RFID switch can be used to permit the devices to transmitone at a time as discussed below.

Considering the time-multiplexing case, varying the length of the SAWdevice and thus the delay before retransmission can separate differentclasses of devices. All seat sensors can have one delay which would bedifferent from tire monitors or light switches etc. Such devices canalso be separated by receiving antenna location.

Referring now to FIGS. 29A and 29B, a first embodiment of a valve cap149 including a tire pressure monitoring system in accordance with theinvention is shown generally at 10 in FIG. 29A. A tire 140 has aprotruding, substantially cylindrical valve stem 141 which is shown in apartial cutaway view in FIG. 29A. The valve stem 141 comprises a sleeve142 and a tire valve assembly 144. The sleeve 142 of the valve stem 141is threaded on both its inner surface and its outer surface. The tirevalve assembly 144 is arranged in the sleeve 142 and includes threads onan outer surface which are mated with the threads on the inner surfaceof the sleeve 142. The valve assembly 144 comprises a valve seat 143 anda valve pin 145 arranged in an aperture in the valve seat 143. The valveassembly 144 is shown in the open condition in FIG. 29A whereby airflows through a passage between the valve seat 143 and the valve pin145.

The valve cap 149 includes a substantially cylindrical body 148 and isattached to the valve stem 141 by means of threads arranged on an innercylindrical surface of body 148 which are mated with the threads on theouter surface of the sleeve 142. The valve cap 149 comprises a valve pindepressor 153 arranged in connection with the body 148 and a SAWpressure sensor 150. The valve pin depressor 153 engages the valve pin145 upon attachment of the valve cap 149 to the valve stem 141 anddepresses it against its biasing spring, not shown, thereby opening thepassage between the valve seat 143 and the valve pin 145 allowing air topass from the interior of tire 140 into a reservoir or chamber 151 inthe body 148. Chamber 151 contains the SAW pressure sensor 150 asdescribed in more detail below.

Pressure sensor 150 can be an absolute pressure-measuring device. If so,it can function based on the principle that the increase in air pressureand thus air density in the chamber 151 increases the mass loading on aSAW device changing the velocity of surface acoustic wave on thepiezoelectric material. The pressure sensor 150 is therefore positionedin an exposed position in the chamber 151. This effect is small andgenerally requires that a very thin membrane is placed over the SAW thatabsorbs oxygen or in some manner increases the loading onto the surfaceof the SAW as the pressure increases.

A second embodiment of a valve cap 10′ in accordance with the inventionis shown in FIG. 29B and comprises a SAW strain sensing device 154 thatis mounted onto a flexible membrane 152 attached to the body 148 of thevalve cap 149 and in a position in which it is exposed to the air in thechamber 151. When the pressure changes in chamber 151, the deflection ofthe membrane 152 changes thereby changing the strain in the SAW device154. This changes the path length that the waves must travel which inturn changes the natural frequency of the SAW device or the delaybetween reception of an interrogating pulse and its retransmission.

Strain sensor 154 is thus a differential pressure-measuring device. Itfunctions based on the principle that changes in the flexure of themembrane 152 can be correlated to changes in pressure in the chamber 151and thus, if an initial pressure and flexure are known, the change inpressure can be determined from the change in flexure or strain.

FIGS. 29A and 29B therefore illustrate two different methods of using aSAW sensor in a valve cap for monitoring the pressure inside a tire. Apreferred manner in which the SAW sensors 150,154 operate is discussedmore fully below but briefly, each sensor 150,154 includes an antennaand an interdigital transducer which receives a wave via the antennafrom an interrogator which proceeds to travel along a substrate. Thetime in which the waves travel across the substrate and return to theinterdigital transducer is dependent on the temperature, the loading onthe substrate (in the embodiment of FIG. 29A) or the flexure of membrane152 (in the embodiment of FIG. 29B). The antenna transmits a return wavewhich is received and the time delay between the transmitted andreturned wave is calculated and correlated to the pressure in thechamber 151. In order to keep the SAW devices as small as possible forthe tire calve cap design, the preferred mode of SAW operation is theresonant frequency mode where a change in the resonant frequency of thedevice is measured.

Sensors 150 and 154 are electrically connected to the metal valve cap149 that is electrically connected to the valve stem 141. The valve stem141 is electrically isolated from the tire rim and can thus serve as anantenna for transmitting radio frequency electromagnetic signals fromthe sensors 150 and 154 to a vehicle mounted interrogator, not shown, tobe described in detail below. As shown in FIG. 29A, a pressure seal 155is arranged between an upper rim of the sleeve 142 and an inner shoulderof the body 148 of the valve cap 149 and serves to prevent air fromflowing out of the tire 140 to the atmosphere.

The speed of the surface acoustic wave on the piezoelectric substratechanges with temperature in a predictable manner as well as withpressure. For the valve cap implementations, a separate SAW device canbe attached to the outside of the valve cap and protected with a coverwhere it is subjected to the same temperature as the SAW sensors 150 or154 but is not subject to pressure or strain. This requires that eachvalve cap comprise two SAW devices, one for pressure sensing and anotherfor temperature sensing. Since the valve cap is exposed to ambienttemperature, a preferred approach is to have a single device on thevehicle which measures ambient temperature outside of the vehiclepassenger compartment. Many vehicles already have such a temperaturesensor. For those installations where access to this temperature data isnot convenient, a separate SAW temperature sensor can be mountedassociated with the interrogator antenna, as illustrated below, or someother convenient place.

Although the valve cap 149 is provided with the pressure seal 155, thereis a danger that the valve cap 149 will not be properly assembled ontothe valve stem 141 and a small quantity of the air will leak over time.FIG. 30 provides an alternate design where the SAW temperature andpressure measuring devices are incorporated into the valve stem. Thisembodiment is thus particularly useful in the initial manufacture of atire.

The valve stem assembly is shown generally at 160 and comprises a brassvalve stem 144 which contains a tire valve assembly 142. The valve stem144 is covered with a coating 161 of a resilient material such asrubber, which has been partially removed in the drawing. A metalconductive ring 162 is electrically attached to the valve stem 144. Arubber extension 163 is also attached to the lower end of the valve stem144 and contains a SAW pressure and temperature sensor 164. The SAWpressure and temperature sensor 164 can be of at least two designswherein the SAW sensor is used as an absolute pressure sensor as shownin FIG. 30A or an as a differential sensor based on membrane strain asshown in FIG. 30B.

In FIG. 30A, the SAW sensor 164 comprises a capsule 172 having aninterior chamber in communication with the interior of the tire via apassageway 170. A SAW absolute pressure sensor 167 is mounted onto oneside of a rigid membrane or separator 171 in the chamber in the capsule172. Separator 171 divides the interior chamber of the capsule 172 intotwo compartments 165 and 166, with only compartment 165 being in flowcommunication with the interior of the tire. The SAW absolute pressuresensor 167 is mounted in compartment 165 which is exposed to thepressure in the tire through passageway 170. A SAW temperature sensor168 is attached to the other side of the separator 171 and is exposed tothe pressure in compartment 166. The pressure in compartment 166 isunaffected by the tire pressure and is determined by the atmosphericpressure when the device was manufactured and the effect of temperatureon this pressure. The speed of sound on the SAW temperature sensor 168is thus affected by temperature but not by pressure in the tire.

The operation of SAW sensors 167 and 168 is discussed elsewhere morefully but briefly, since SAW sensor 167 is affected by the pressure inthe tire, the wave which travels along the substrate is affected by thispressure and the time delay between the transmission and reception of awave can be correlated to the pressure. Similarly, since SAW sensor 168is affected by the temperature in the tire, the wave which travels alongthe substrate is affected by this temperature and the time delay betweenthe transmission and reception of a wave can be correlated to thetemperature. Similarly, the natural frequency of the SAW device willchange due to the change in the SAW dimensions and that naturalfrequency can be determined if the interrogator transmits a chirp.

FIG. 30B illustrates an alternate and preferred configuration of sensor164 where a flexible membrane 173 is used instead of the rigid separator171 shown in the embodiment of FIG. 30A, and a SAW device is mounted onflexible member 173. In this embodiment, the SAW temperature sensor 168is mounted to a different wall of the capsule 172. A SAW device 169 isthus affected both by the strain in membrane 173 and the pressure in thetire. Normally, the strain effect will be much larger with a properlydesigned membrane 173.

The operation of SAW sensors 168 and 169 is discussed elsewhere morefully but briefly, since SAW sensor 168 is affected by the temperaturein the tire, the wave which travels along the substrate is affected bythis temperature and the time delay between the transmission andreception of a wave can be correlated to the temperature. Similarly,since SAW sensor 169 is affected by the pressure in the tire, the wavewhich travels along the substrate is affected by this pressure and thetime delay between the transmission and reception of a wave can becorrelated to the pressure.

In both of the embodiments shown in FIGS. 30A and 30B, a separatetemperature sensor is illustrated. This has two advantages. First, itpermits the separation of the temperature effect from the pressureeffect on the SAW device. Second, it permits a measurement of tiretemperature to be recorded. Since a normally inflated tire canexperience excessive temperature caused, for example, by an overloadcondition, it is desirable to have both temperature and pressuremeasurements of each vehicle tire

The SAW devices 167, 168 and 169 are electrically attached to the valvestem 144 which again serves as an antenna to transmit radio frequencyinformation to an interrogator. This electrical connection can be madeby a wired connection; however, the impedance between the SAW devicesand the antenna may not be properly matched. An alternate approach asdescribed in Varadan, V. K. et al., “Fabrication, characterization andtesting of wireless MEMS-IDT based micro accelerometers”, Sensors andActuators A 90 (2001) p. 7-19, 2001 Elsevier Netherlands, is toinductively couple the SAW devices to the brass tube.

Although an implementation into the valve stem and valve cap exampleshave been illustrated above, an alternate approach is to mount the SAWtemperature and pressure monitoring devices elsewhere within the tire.Similarly, although the tire stem in both cases above can serve as theantenna, in many implementations, it is preferable to have a separatelydesigned antenna mounted within or outside of the vehicle tire. Forexample, such an antenna can project into the tire from the valve stemor can be separately attached to the tire or tire rim either inside oroutside of the tire. In some cases, it can be mounted on the interior ofthe tire on the sidewall.

A more advanced embodiment of a tire monitor in accordance with theinvention is illustrated generally at 40 in FIGS. 31 and 31A. Inaddition to temperature and pressure monitoring devices as described inthe previous applications, the tire monitor assembly 175 comprises anaccelerometer of any of the types to be described below which isconfigured to measure either or both of the tangential and radialaccelerations. Tangential accelerations as used herein generally meansaccelerations tangent to the direction of rotation of the tire andradial accelerations as used herein generally means accelerations towardor away from the wheel axis.

In FIG. 31, the tire monitor assembly 175 is cemented, or otherwiseattached, to the interior of the tire opposite the tread. In FIG. 31A,the tire monitor assembly 175 is inserted into the tire opposite thetread during manufacture.

Superimposed on the acceleration signals will be vibrations introducedinto tire from road interactions and due to tread separation and otherdefects. Additionally, the presence of the nail or other object attachedto the tire will, in general, excite vibrations that can be sensed bythe accelerometers. When the tread is worn to the extent that the wirebelts 176 begin impacting the road, additional vibrations will beinduced.

Through monitoring the acceleration signals from the tangential orradial accelerometers within the tire monitor assembly 175,delamination, a worn tire condition, imbedded nails, other debrisattached to the tire tread, hernias, can all be sensed. Additionally, aspreviously discussed, the length of time that the tire tread is incontact with the road opposite tire monitor 175 can be measured and,through a comparison with the total revolution time, the length of thetire footprint on the road can be determined. This permits the load onthe tire to be measured, thus providing an indication of excessive tireloading. As discussed above, a tire can fail due to over-loading evenwhen the tire interior temperature and pressure are within acceptablelimits. Other tire monitors cannot sense such conditions.

In the discussion above, the use of the tire valve stem as an antennahas been discussed. An antenna can also be placed within the tire whenthe tire sidewalls are not reinforced with steel. In some cases and forsome frequencies, it is sometimes possible to use the tire steel bead orsteel belts as an antenna, which in some cases can be coupled toinductively. Alternately, the antenna can be designed integral with thetire beads or belts and optimized and made part of the tire duringmanufacture.

Although the discussion above has centered on the use of SAW devices,the configurations of FIGS. 31A and 31B can also be effectivelyaccomplished with other pressure, temperature and accelerometer sensorsparticularly those based on RFID technology. One of the advantages ofusing SAW devices is that they are totally passive thereby eliminatingthe requirement of a battery. For the implementation of tire monitorassembly 175, the acceleration can also be used to generate sufficientelectrical energy to power a silicon microcircuit. In thisconfiguration, additional devices, typically piezoelectric devices, areused as a generator of electricity that can be stored in one or moreconventional capacitors or ultra-capacitors. Other types of electricalgenerators can be used such as those based on a moving coil and amagnetic field etc. A PVDF piezoelectric polymer can also, andpreferably, be used to generate electrical energy based on the flexureof the tire as described below.

FIG. 32 illustrates an absolute pressure sensor based on surfaceacoustic wave (SAW) technology. A SAW absolute pressure sensor 180 hasan interdigital transducer (IDT) 181 which is connected to antenna 182.Upon receiving an RF signal of the proper frequency, the antenna 182induces a surface acoustic wave in the material 183 which can be lithiumniobate, quartz, zinc oxide, or other appropriate piezoelectricmaterial. As the wave passes through a pressure sensing area 184 formedon the material 183, its velocity is changed depending on the airpressure exerted on the sensing area 184. The wave is then reflected byreflectors 185 where it returns to the IDT 181 and to the antenna 182for retransmission back to the interrogator. The material in thepressure sensing area 184 can be a thin (such as one micron) coating ofa polymer that absorbs or reversibly reacts with oxygen or nitrogenwhere the amount absorbed depends on the air density.

In FIG. 32A, two additional sections of the SAW device, designated 186and 187, are provided such that the air pressure affects sections 186and 187 differently than pressure sensing area 184. This is achieved byproviding three reflectors. The three reflecting areas cause threereflected waves to appear, 189, 190 and 191 when input wave 192 isprovided. The spacing between waves 189 and 190, and between waves 190and 191 provides a measure of the pressure. This construction of apressure sensor may be utilized in the embodiments of FIGS. 29A-31 or inany embodiment wherein a pressure measurement by a SAW device isobtained.

There are many other ways in which the pressure can be measured based oneither the time between reflections or on the frequency or phase changeof the SAW device as is well known to those skilled in the art. FIG.32B, for example, illustrates an alternate SAW geometry where only twosections are required to measure both temperature and pressure. Thisconstruction of a temperature and pressure sensor may be utilized in theembodiments of FIGS. 29A-31 or in any embodiment wherein both a pressuremeasurement and a temperature measurement by a single SAW device isobtained.

Another method where the speed of sound on a piezoelectric material canbe changed by pressure was first reported in Varadan et al.,“Local/Global SAW Sensors for Turbulence” referenced above. Thisphenomenon has not been applied to solving pressure sensing problemswithin an automobile until now. The instant invention is believed to bethe first application of this principle to measuring tire pressure, oilpressure, coolant pressure, pressure in a gas tank, etc. Experiments todate, however, have been unsuccessful.

In some cases, a flexible membrane is placed loosely over the SAW deviceto prevent contaminants from affecting the SAW surface. The flexiblemembrane permits the pressure to be transferred to the SAW devicewithout subjecting the surface to contaminants. Such a flexible membranecan be used in most if not all of the embodiments described herein.

A SAW temperature sensor 195 is illustrated in FIG. 33. Since the SAWmaterial, such as lithium niobate, expands significantly withtemperature, the natural frequency of the device also changes. Thus, fora SAW temperature sensor to operate, a material for the substrate isselected which changes its properties as a function of temperature,i.e., expands with increasing temperature. Similarly, the time delaybetween the insertion and retransmission of the signal also variesmeasurably. Since speed of a surface wave is typically 100,000 timesslower then the speed of light, usually the time for the electromagneticwave to travel to the SAW device and back is small in comparison to thetime delay of the SAW wave and therefore the temperature isapproximately the time delay between transmitting electromagnetic waveand its reception.

An alternate approach as illustrated in FIG. 33A is to place athermistor 197 across an interdigital transducer (IDT) 196, which is nownot shorted as it was in FIG. 33. In this case, the magnitude of thereturned pulse varies with the temperature. Thus, this device can beused to obtain two independent temperature measurements, one based ontime delay or natural frequency of the device 195 and the other based onthe resistance of the thermistor 197.

When some other property such as pressure is being measured by thedevice 198 as shown in FIG. 33B, two parallel SAW devices can be used.These devices are designed so that they respond differently to one ofthe parameters to be measured. Thus, SAW device 199 and SAW device 200can be designed to both respond to temperature and respond to pressure.However, SAW device 200, which contains a surface coating, will responddifferently to pressure than SAW device 199. Thus, by measuring naturalfrequency or the time delay of pulses inserted into both SAW devices 199and 200, a determination can be made of both the pressure andtemperature, for example. Naturally, the device which is renderedsensitive to pressure in the above discussion could alternately berendered sensitive to some other property such as the presence orconcentration of a gas, vapor, or liquid chemical as described in moredetail below.

An accelerometer that can be used for either radial or tangentialacceleration in the tire monitor assembly of FIG. 31 is illustrated inFIGS. 34 and 34A. The design of this accelerometer is explained indetail in Varadan, V. K. et al., “Fabrication, characterization andtesting of wireless MEMS-IDT based microaccelerometers” referenced aboveand will not be repeated herein.

FIG. 35 illustrates a central antenna mounting arrangement forpermitting interrogation of the tire monitors for four tires and issimilar to that described in U.S. Pat. No. 4,237,728. An antenna package202 is mounted on the underside of the vehicle and communicates withdevices 203 through their antennas as described above. In order toprovide for antennas both inside (for example for weight sensorinterrogation) and outside of the vehicle, another antenna assembly (notshown) can be mounted on the opposite side of the vehicle floor from theantenna assembly 202. Devices 203 may be any of the tire monitoringdevices described above.

FIG. 35A is a schematic of the vehicle shown in FIG. 35. The antennapackage 202, which can be considered as an electronics module, containsa time domain multiplexed antenna array that sends and receives datafrom each of the five tires (including the spare tire), one at a time.It comprises a microstrip or stripline antenna array and amicroprocessor on the circuit board. The antennas that face each tireare in an X configuration so that the transmissions to and from the tirecan be accomplished regardless of the tire rotation angle.

Although piezoelectric SAW devices normally use rigid material such asquartz or lithium niobate, it is also possible to utilize PVDF providedthe frequency is low. A piece of PVDF film can also be used as a sensorof tire flexure by itself. Such a sensor is illustrated in FIGS. 36 and36A at 204. The output of flexure of the PVDF film can be used to supplypower to a silicon microcircuit that contains pressure and temperaturesensors. The waveform of the output from the PVDF film also providesinformation as to the flexure of an automobile tire and can be used todiagnose problems with the tire as well as the tire footprint in amanner similar to the device described in FIG. 31. In this case,however, the PVDF film supplies sufficient power to permit significantlymore transmission energy to be provided. The frequency and informationalcontent can be made compatible with the SAW interrogator described abovesuch that the same interrogator can be used. The power available for theinterrogator, however, can be significantly greater thus increasing thereliability and reading range of the system. In order to obtainsignificant energy based on the flexure of a PVDF film, many layers ofsuch a film may be required.

Instead of a PVDF film, other piezo or ferroelectric substrates couldalso be used, as would be appreciated by those skilled in the art. ThePVDF film could be arranged in the rubber substrate, or other flexiblesubstrate, defining the side walls of the tire.

Referring now to FIG. 98, as mentioned above, the output of flexure ofthe PVDF film during rotation of the tire can be used to supply power toa silicon microcircuit that contains pressure and temperature sensors.As shown in FIG. 98, the tire 205 would include the PVDF film or anotherpower generating system 206 arranged on, in connection with or within itand which would provide power to both the SAW device 207 and an energystorage device 208 during rotation of the tire 205. Typically, powerwould first be provided to the SAW device 207 when it is operative andthen excess power provided to the energy storage device 208. SAW device207 is connected to an antenna 209 and provides a modified signal inresponse to a signal received by the antenna 209, the signal beingmodified as a function of the property or properties being monitored bythe SAW device 207. SAW device 207 may be used to monitor pressure ofthe tire, temperature of the tire, other properties or a combination ofsuch properties. Antenna 209 is a wireless transmission component whichis capable of receiving a wireless signal from an interrogator andtransmitting a modified signal originating from the SAW device 207 isresponse.

SAW device 207, energy storage device 208 and antenna 209 are part of acircuit 333 powered by power generating system 206. Circuit 333optionally also includes one or more switches 334 between the SAW device208 and the antenna 209 and a circulator 335 between the SAW device 208and the antenna 209. Both switches and a circulator can be interposedbetween the SAW device 208 and the antenna 209. Additional details aboutthe circulator are described with reference to FIGS. 42-44B. Additionaldetails about the operation of switches are described with reference toFIGS. 16D, 16E and 16G.

Instead of arranging the power generating system on a tire 205, it couldalternatively be arranged on any movable substrate which is part of avehicle. Energy could be generated upon movement of the substrate whichmight be rotational movement, as in the case of the tire, or vibrationalmovement.

Moreover, instead of a flexible pad, the power generating system couldbe any type of energy harvesting system including one having a movablemass which moves during movement of a substrate or housing in connectionwith which or to which it is mounted, with the movement of the massresulting in induction-generated power.

As mentioned above with respect to FIG. 16G, the circuit 333 has apassive mode and an active mode. In the active mode, either the tire 205is rotating and power is provided to the circuit 333 to enable full useof the SAW device 207 directly from the power generating system 206 orthe tire is not rotating and energy is provided to enable full use ofthe SAW device 207 from the energy storage device 208 (note that theenergy storage device 208 may be a battery or other type of energystorage device which is not necessarily charged by the power generatingsystem 206). Thus, the circuit is in the active mode when either thetire 205 is rotating or the energy storage device 208 containssufficient power. The circuit enters into the passive mode when there isinsufficient power in the energy storage device 208 for full use of theSAW device. In this case, the SAW device 207 receives energy from thesignal received by the antenna 209, which often is insufficient toenable full use of the SAW device 207. For example, the energy providedby the received signal may be insufficient to enable an identificationcode to be transmitted via the antenna 209 in addition to the modifiedsignal from the SAW device 207. Specifically, in the passive mode, theenergy provided by the signal received by antenna 209 may not beadequate to enable operation of an RFID device 159 in the circuit 333and thus an identification code may not be sent. That is, in the passivemode, there may not be sufficient available energy from aradio-frequency signal received by antenna 209 to power even an RFIDswitch

Thus, in the passive mode, the circuit 333 can return a modified signalvia antenna 209 which provides or enables a determination of the tirepressure, for example, or the mere fact that any signal is returnedmeans that the tire pressure is too low. In this case, for a typicalvehicle with several tires, only those tires with low pressure willreturn a signal when operating in the passive mode, i.e., when thevehicle is stationary. This prevents confusion between tires if all ofthem were transmitting in the passive mode.

There is a general problem with tire pressure monitors as well assystems that attempt to interrogate passive SAW or electronic RFID typedevices in that the FCC severely limits the frequencies and radiatingpower that can be used. Once it becomes evident that these systems willeventually save many lives, the FCC can be expected to modify theirposition. In the meantime, various schemes can be used to help alleviatethis problem. The lower frequencies that have been opened for automotiveradar permit higher power to be used and they could be candidates forthe devices discussed above. It is also possible, in some cases, totransmit power on multiple frequencies and combine the received power toboost the available energy. Energy can of course be stored andperiodically used to drive circuits and work is ongoing to reduce thevoltage required to operate semiconductors. The devices of thisinvention will make use of some or all of these developments as theytake place.

If the vehicle has been at rest for a significant time period, powerwill leak from the storage capacitors and will not be available fortransmission. However, a few tire rotations are sufficient to providethe necessary energy.

FIG. 37 illustrates another version of a tire temperature and/orpressure monitor 210. Monitor 210 may include at an inward end, any oneof the temperature transducers or sensors described above and/or any oneof the pressure transducers or sensors described above, or any one ofthe combination temperature and pressure transducers or sensorsdescribed above.

The monitor 210 has an elongate body attached through the wheel rim 213typically on the inside of the tire so that the under-vehicle mountedantenna(s) have a line of sight view of antenna 214. Monitor 210 isconnected to an inductive wire 212, which matches the output of thedevice with the antenna 214, which is part of the device assembly.Insulating material 211 surrounds the body which provides an air tightseal and prevents electrical contact with the wheel rim 213.

FIG. 38 illustrates an alternate method of applying a force to a SAWpressure sensor from the pressure capsule and FIG. 38A is a detailedview of area 38A in FIG. 38. In this case, the diaphragm in the pressurecapsule is replaced by a metal ball 643 which is elastically held in ahole by silicone rubber 642. The silicone rubber 643 can be loaded witha clay type material or coated with a metallic coating to reduce gasleakage past the ball. Changes in pressure in the pressure capsule acton the ball 642 causing it to deflect and act on the SAW device 637changing the strain therein.

An alternate method to that explained with reference to FIG. 38A using athin film of lithium niobate 644 is illustrated in FIG. 39. In both ofthese cases, the lithium niobate 644 is placed within the pressurechamber which also contains the reference air pressure 640. A passage645 for pressure feed is provided. In the embodiments shown in FIGS. 38,38A and 39, the pressure and temperature measurement is done ondifferent parts of a single SAW device whereas in the embodiment shownin FIGS. 30A and 30B, two separate SAW devices are used.

FIG. 40 illustrates a preferred four pulse design of a tire temperatureand pressure monitor based on SAW and FIG. 40A illustrates the echopulse magnitudes from the design of FIG. 40.

FIG. 41 illustrates an alternate shorter preferred four pulse design ofa tire temperature and pressure monitor based on SAW and FIG. 41Aillustrates the echo pulse magnitudes from the design of FIG. 41. Theinnovative design of FIG. 41 is an improved design over that of FIG. 40in that the length of the SAW is reduced by approximately 50%. This notonly reduces the size of the device but also its cost.

1.4.1 Antenna Considerations

As discussed above in section 1.3.1, antennas are a very important partof SAW and RFID wireless devices such as tire monitors. The discussionof that section applies particularly to tire monitors but need not berepeated here.

1.4.2 Boosting Signals

FIG. 42 illustrates an arrangement for providing a boosted signal from aSAW device is designated generally as 220 and comprises a SAW device221, a circulator 222 having a first port or input channel designatedPort A and a second port or input channel designated Port B, and anantenna 223. The circulator 222 is interposed between the SAW device 221and the antenna 223 with Port A receiving a signal from the antenna 223and Port B receiving a signal from the SAW device 221.

In use, the antenna 223 receives a signal when a measurement from theSAW device 221 is wanted and a signal from the antenna 16 is switchedinto Port A where it is amplified and output to Port B. The amplifiedsignal from Port B is directed to the SAW device 221 for the SAW toprovide a delayed signal indicative of the property or characteristicmeasured or detected by the SAW device 221. The delayed signal isdirected to Port B of the circulator 222 which boosts the delayed signaland outputs the boosted, delayed signal to Port A from where it isdirected to the antenna 16 for transmission to a receiving andprocessing module 224.

The receiving and processing module 224 transmits the initial signal tothe antenna 16 when a measurement or detection by the SAW device 221 isdesired and then receives the delayed, boosted signal from the antenna223 containing information about the measurement or detection performedby the SAW device 221.

The circuit which amplifies the signal from the antenna 223 and thedelayed signal from the SAW device 221 is shown in FIG. 43. As shown,the circuit provides an amplification of approximately 6 db in eachdirection for a total, round-trip signal gain of 12 db. This circuitrequires power as described herein which can be supplied by a battery orgenerator. A detailed description of the circuit is omitted as it willbe understood by those skilled in the art.

As shown in FIG. 44, the circuit of FIG. 43 includes electroniccomponents arranged to form a first signal splitter 225 in connectionwith the first port Port A adjacent the antenna 223 and a second signalsplitter 226 in connection with the second port Port B adjacent the SAWdevice 221. Electronic components are also provided to amplify thesignal being directed from the antenna 223 to the SAW device 221 (gaincomponent 227) and to amplify the signal being directed from the SAWdevice 221 to the antenna 223 (gain component 228).

As shown in FIG. 44A, the two-port circulator 222 can be constructed ofa pair of active or passive three-port circulators 216A, 216B.Circulator 216A has a first port defining or coupled to Port A of FIG.42, a second port leading to an input of amplifier 217A, and a thirdport leading from an output of a second amplifier 217B. Circulator 216Bhas a first port defining or coupled to Port B, a second port leading toan input of amplifier 217B and a third port leading from the output ofamplifier 217A. Signal paths are represented by arrows in FIG. 44A. Inoperation, a signal from the antenna 223 goes into Port A and then intoport 1 of circulator 216A and out of circulator 216A via its secondport. The signal from circulator 216B is amplified by amplifier 217A andsent to the third port of circulator 216B where it comes out on port 1to the SAW device 221 via Port B. A signal from the SAW device 221 goesinto Port B and then into port of circulator 216B and out of circulator216B via its second port. The signal from circulator 216B is amplifiedby amplifier 217B and sent to the third port of circulator 216A where itcomes out on port 1 to the antenna 223 via Port A. In one embodiment,amplifiers 217A, 217B typically have a gain of about 15 dB so that theround trip gain is about 30 B. Of course, the gain of amplifiers 217A,217B is selectable as desired or required for the situation. Althoughthis circuit is an active circuit, i.e., power is required to operate,passive circuits can also be designed to accomplished the same result.

FIG. 44B shows an exemplifying embodiment of an active circuitrepresenting each circulator 216A, 216B.

The circuit is powered by a battery, of either a conventional type or anatomic battery (as discussed below), or, when used in connection with atire of the vehicle, a capacitor, super capacitor or ultracapacitor(super cap) and charged by, for example, rotation of the tire ormovement of one or more masses as described in more detail elsewhereherein. Thus, when the vehicle is moving, the circuit is in an activemode and a capacitor in the circuit is charged. On the other hand, whenthe vehicle is stopped, the circuit is in a passive mode and thecapacitor is discharged. In either case, the pressure measurement in thetire can be transmitted to the interrogator.

Instead of a SAW device 221, Port B can be connected to an RFID (radiofrequency identification) tag or another electrical component whichprovides a response based on an input signal and/or generates a signalin response to a detected or measured property or characteristic.

Also, the circuit can be arranged on other movable structures, otherthan a vehicle tire, whereby the movement of the structure causescharging of the capacitor and when the structure is not moving, thecapacitor discharges and provides energy. Other movable structuresinclude other parts of a vehicle including trailers and containers,boats, airplanes etc., a person, animal, wind or wave-operated device,tree or any structure, living or not, that can move and thereby permit aproperly designed energy generator to generate electrical energy.Naturally other sources of environmental energy can be used consistentwith the invention such as wind, solar, tidal, thermal, acoustic etc.

FIGS. 45 and 46 show a circuit used for charging a capacitor duringmovement of a vehicle which may be used to power the boostingarrangement of FIG. 42 or for any other application in which energy isrequired to power a component such as a component of a vehicle. Theenergy can be generated by the motion of the vehicle so that thecapacitor has a charging mode when the vehicle is moving (the activemode) and a discharge, energy-supplying phase when the vehicle isstationary or not moving sufficient fast to enable charging (the passivemode).

As shown in FIGS. 45 and 46, the charging circuit 230 has a chargingcapacitor 231 and two masses 232,233 (FIG. 45) mounted perpendicular toone another (one in a direction orthogonal or perpendicular to theother). The masses 232,233 are each coupled to mechanical-electricalconverters 234 to convert the movement of the mass into electric signalsand each converter 234 is coupled to a bridge rectifier 235. Bridgerectifiers 235 may be the same as one another or different and are knownto those skilled in the art. As shown, the bridge rectifiers 235 eachcomprise four Zener diodes 236. The output of the bridge rectifiers 235is passed to the capacitor 231 to charge it. A Zener diode 44 isarranged in parallel with the capacitor 231 to prevent overcharging ofthe capacitor 231. Instead of capacitor 231, multiple capacitors or arechargeable battery or other energy-storing device or component can beused.

An RF MEMS or equivalent switch, not shown, can be added to switch thecirculator into and out of the circuit slightly increasing theefficiency of the system when power is not present. Heretofore, RF MEMSswitches have not been used in the tire, RFID or SAW sensor environmentsuch as for TPM power and antenna switching. One example of an RF MEMSswitch is manufactured by Teravicta Technologies Inc. The company'sinitial product, the TT612, is a 0 to 6 GHz RF MEMS single-pole,double-throw (SPDT) switch. It has a loss of 0.14-dB at 2-GHz, goodlinearity and a power handling capability of three watts continuous, allenclosed within a surface mount package.

1.4.3 Energy Generation

There are a variety of non-conventional battery and battery less powersources for the use with tire monitors, some of which also will operatewith other SAW sensors. One method is to create a magnetic field nearthe tire and to place a coil within the tire that passes through themagnetic field and thereby generate a current. It may even be possibleto use the earth's magnetic field. Another method is to create anelectric field and capacitively couple to a circuit within the tire thatresponds to an alternating electric field external to the tire andthereby induce a current in the circuit within the tire. One prior artsystem uses a weight that responds to the cyclic change in the gravityvector as the tire rotates to run a small pump that inflates the tire.That principle can also be used to generate a current as the weightmoves back and forth.

One interesting possibility is to use the principle of regenerativebraking to generate energy within a tire in a manner similar to the waysuch systems are in use on electric vehicles. Such a device can generateenergy within each tire every time the vehicle is stopped. Such aregenerative unit can be a small device used in conjunction with aprimary regenerative unit that could reside on the vehicle. Such a unitcan be designed to operate just as the brakes are being applied and makeuse of the slip between the fixed and movable surfaces of the brake.Many other methods will now be obvious wherein the relative motion ofthe two engaging surfaces of a brake assembly can be used to generatepower. Another method, for example, could be to generate energyinductively between the moving and fixed brake surfaces or othersurfaces that move relative to each other. A further method to generateenergy could be based on movement of the plates of a capacitor relativeto each other to generate a current. Many of these methods could be partof or separate from the brake assembly as desired by theskilled-in-the-art designer.

A novel method is to use a small generator that can be based on MEMS orother principles in a manner to that discussed in Gilleo, Ken, “NeverNeed Batteries Again” appearing athttp://www.e-insite.net/epp/index.asp?layout=article&articleid=CA219070.This article describes a MEMS energy extractor that can be placed on anyvibrating object where it will extract energy from the vibrations. Sucha device would need to be especially designed for use in tiremonitoring, or other vehicle or non-vehicle application, in order tooptimize the extraction of energy. The device would not be limited tothe variations in the gravity vector, although it could make use of it,but can also generate electricity from all motions of the tire includingthose caused by bumps and uneven roadways. The greater the vibration,the more electric power that will be generated.

FIGS. 47, 47A and 47B illustrate a tire pumping system having a housingfor mounting external to a tire, e.g., on the wheel rim. This particulardesign is optimized for reacting to the variation in gravitationalvector as the wheel rotates and is shown in the pumping designimplementation mode. The housing includes a mass 241 responsive to thegravitational vector as the wheel rotates and a piston rod connected to,part of or formed integral with the mass 241. The mass 241 may thus havean annular portion (against which springs 242 bear) and an elongatedcylindrical portion (movable in chambers) as shown, i.e., the piston rodor similar structure. The mass 241 alternately compresses the springs242, one on each side of the mass 241, and draws in air through inletvalves 244 and exhausts air through exhaust valves 245 to enter the tirethrough nipples 243. Mass 241 is shown smaller that it would in fact be.To minimize the effects of centrifugal acceleration, the mass 241 isplaced as close as possible to the wheel axis.

When the mass 241 moves in one direction, for example to the left inFIGS. 47A and 47B, the piston rod fixed to the mass 241 moves to theleft so that air is drawn into a chamber defined in a cylinder throughthe inlet valve 244. Upon subsequent rotation of the wheel, the mass 241moves to the right causing the piston rod to move to the right and forcethe air previously drawn into chamber through an exhaust valve 245 andinto a tube leading to the nipple 243 and into the tire. During thissame rightward movement of the piston rod, air is drawn into a chamberdefined in the other cylinder through the other inlet valve 244. Uponsubsequent rotation of the wheel, the mass 241 moves to the left causingthe piston rod to move to the left and force the air previously drawninto chamber through an exhaust valve 245 and into a second tube leadingto the other nipple 243 and into the tire. In this manner, thereciprocal movement of the mass 241 results in inflation of the tire.

Valves 244 are designed as inlet valves and do not allow flow from thechambers to the surrounding atmosphere. Valves 245 are designed asexhaust valves and do not allow flow from the tubes into the respectivechamber.

In operation, other forces such as caused by the tire impacting a bumpin the road will also effect the pump operation and in many cases itwill dominate. As the wheel rotates (and the mass 241 moves back andforth for example at a rate of mg cos (ωt), the tire is pumped up.

In the illustrated embodiment, the housing includes two cylinders eachdefining a respective chamber, two springs 242, two tubes and an inletand exhaust valve for each chamber. It is possible to provide a housinghaving only a single cylinder defining one chamber with inlet andexhaust valves, and associated tube leading to a nipple of the tire. Thetire pumping system would then include only a single piston rod and asingle spring.

The mass would thus inflate the tire at half the inflation rate when twocylinders are provided (assuming the same size cylinder is provided). Itis also contemplated that a housing having three cylinders andassociated pumping structure could be provided. The number of cylinderscould depend on the number of nipples on the tire. Also, it is possibleto have multiple cylinders leading to a common tube leading to a commonnipple.

Alternately, instead of a pump which is operated based on movement ofthe mass, an electricity generating system can be provided which powersa pump or other device on the vehicle. FIG. 47C shows an electricitygenerating system in which the mass 241 is magnetized and includes apiston rod 238 and coils 262 are wrapped around cylinders 246A, 246Bwhich define chambers 239A, 239B in which the piston rod 238 moves. Asthe tire rotates, the system generates electricity and charges a storageor load device 263 as described above. Thus, in this embodiment of anelectricity generating system, the housing 240 is mounted external tothe tire, or within the tire, and includes one or more cylinders 246A,246B each defining a chamber 239A, 239B. The mass 241 is movable in thehousing 240 in response to rotation thereof and includes a magneticpiston rod 238 movable in each chamber 239A, 239B. The magnetic pistonrod 238 may be formed integral with or separate from, but connected to,the mass 241. A spring is compressed by the mass 241 upon movementthereof and if two springs 242 are provided, each may be arrangedbetween a respective side of the mass 241 and the housing 240 andcompressed upon movement of the mass 241 in opposite directions. Anenergy storage or load device 263 is connected to each coil 262, e.g.,by wires, so that upon rotation of the tire, the mass 241 moves causingthe piston 238 to move in each chamber 239A, 239B and impart a charge toeach coil 262 which is stored or used by the energy storage or loaddevice 263. When two coils 262 are provided, upon rotation of the tire,the mass 241 moves causing the piston rod 238 to alternately move in thechambers 239A, 239B relative to the coils 262 and impart a chargealternatingly to one or the other of the coils 262 which is stored orused by the energy storage or load device 263.

The energy storage device 263 can be used to power a tire pump 264 andcoupled thereto can be a wire 271, and a tube 252 can be provided tocouple the pump 264 to the nipple 293 of the tire. Obviously, the pump264 must communicate with the atmosphere through the housing walls toprovide an intake air flow.

The housing 240 may be mounted to the wheel rim or tire via any type ofconnection mechanism, such as by bolts or other fasteners through theholes provided. In the alternative, the housing 240 may be integrallyconstructed with the wheel rim.

Non-linear springs 242 can be used to help compensate for the effects ofcentrifugal accelerations. Naturally, this design will work best at lowvehicle speeds or when the road is rough.

FIGS. 48A and 48B illustrate two versions of an RFID tag, FIG. 48A isoptimized for high frequency operation such as a frequency of about 2.4GHz and FIG. 48B is optimized for low frequency operation such as afrequency of about 13.5 MHz. The operation of both of these tags isdescribed in U.S. Pat. No. 6,486,780 and each tag comprises an antenna248, an electronic circuit 247 and a capacitor 249. The circuit 247contains a memory that contains the ID portion of the tag. For thepurposes herein, it is not necessary to have the ID portion of the tagpresent and the tag can be used to charge a capacitor or ultra-capacitor249 which can then be used to boost the signal of the SAW TPM asdescribed above. The frequency of the tag can be set to be the same asthe SAW TPM or it can be different permitting a dual frequency systemwhich can make better use of the available electromagnetic spectrum. Forenergy transfer purposes, a wideband or ultra-wideband system thatallows the total amount of radiation within a particular band to beminimized but spreads the energy over a wide band can also be used.

Other systems that can be used to generate energy include a coil andappropriate circuitry, not shown, that cuts the lines of flux of theearth's magnetic field, a solar battery attached to the tire sidewall,not shown, and a MEMS or other energy-based generators which use thevibrations in the tire. The bending deflection of tread or thedeflection of the tire itself relative to the tire rim can also be usedas sources of energy, as disclosed below. Additionally, the use of a PZTor piezoelectric material with a weight, as in an accelerometer, can beused in the presence of vibration or a varying acceleration field togenerate energy. All of these systems can be used with the boostingcircuit with or without a MEMS RF or other appropriate mechanical orelectronic switch.

FIGS. 49A and 49B illustrate a pad 250 made from a piezoelectricmaterial such as polyvinylidene fluoride (PVDF) that is attached to theinside of a tire adjacent to the tread and between the side walls. OtherPZT or piezoelectric materials can also be used instead of PVDF. As thematerial of the pad 250 flexes when the tire rotates and brings the pad250 close to the ground, a charge appears on different sides of the pad250 thereby creating a voltage that can be used along with appropriatecircuitry, not shown, to charge an energy storage device or power avehicular component. Similarly, as the pad 250 leaves the vicinity ofthe road surface and returns to its original shape, another voltageappears having the opposite polarity thereby creating an alternatingcurrent. The appropriate circuitry 251 coupled to the pad 250 thenrectifies the current and charges the energy storage device, possiblyincorporated within the circuitry 251.

Variations include the use of a thicker layer or a plurality of parallellayers of piezoelectric material to increase the energy generatingcapacity. Additionally, a plurality of pad sections can be joinedtogether to form a belt that stretches around the entire innercircumference of the tire to increase the energy-generating capacity andallow for a simple self-supporting installation. Through a clever choiceof geometry known or readily determinable by those skilled in the art, asubstantial amount of generating capacity can be created and more thanenough power produced to operate the booster as well as other circuitryincluding an accelerometer. Furthermore, PVDF is an inexpensive materialso that the cost of this generator is small. Since substantialelectrical energy can be generated by this system, an electrical pumpcan be driven to maintain the desired tire pressure for all normaldeflation cases. Such a system will not suffice if a tire blowoutoccurs.

A variety of additional features can also be obtained from this geometrysuch as a measure of the footprint of the tire and thus, when combinedwith the tire pressure, a measure of the load on the tire can beobtained. Vibrations in the tire caused by exposed steel belts,indicating tire wear, a nail, bulge or other defect will also bedetectable by appropriate circuitry that monitors the informationavailable on the generated voltage or current. This can also beaccomplished by the system that is powered by the change in distancebetween the tread and the rim as the tire rotates coupled with a measureof the pressure within the tire.

FIGS. 50A-50D illustrate another tire pumping and/or energy-generatingsystem based on the principle that as the tire rotates the distance fromthe rim to the tire tread or ground changes and that fact can be used topump air or generate electricity. In the embodiment shown in FIGS. 50Aand 50B, air from the atmosphere enters a chamber in the housing orcylinder 254 through an inlet or intake valve 255 during the up-strokeof a piston 253, and during the down-stroke of the piston 253, the airis compressed in the chamber in the cylinder 254 and flows out ofexhaust valve 260 into the tire. The piston 253 thus moves at leastpartly in the chamber in the cylinder 254. A conduit is provided in thepiston 253 in connection with the inlet valve 255 to allow the flow ofair from the ambient atmosphere to the chamber in the cylinder 254.

In the electrical energy-generating example (FIG. 50C), a piston 257having a magnet that creates magnet flux travels within a coil 256 (theup and down stroke occur at least partly within the space enclosed bythe coil 256) and electricity is generated. The electricity isrectified, processed and stored as in the above examples. Naturally, theforce available can be substantial as a portion of the entire load onthe tire can be used.

The rod connecting the rim to the device can be designed to flex undersignificant load so that the entire mechanism is not subjected to fullload on the tire if the tire does start going flat. Alternately, afailure mode can be designed into the mechanism so that a replaceablegasket 258, or some other restorable system, permits the rod of thedevice to displace when the tire goes flat as, for example, when a nail259 punctures the tire (see FIG. 50D). This design has a furtheradvantage in that when the piston bottoms out indicating a substantialloss of air or failure of the tire, a once-per-revolution vibration thatshould be clearly noticeable to the driver occurs. Naturally, severaldevices can be used and positioned so that they remain in balance.Alternately this device, or a similar especially designed device, byitself can be used to measure tire deflection and thus a combination oftire pressure and vehicle load.

An alternate approach is to make use of a nuclear microbattery asdescribed in, A. Amit and J. Blanchard “The Daintiest Dynamos”,(http://www.spectrum.ieee.org/WEBONLY/publicfeature/sep04/0904nuc.html#t1)IEEE Spectrum online 2004. Other energy harvesting devices include aninductive based technology from Ferro Solutions Inc. These innovativeideas and more to come are applicable for powering the devices describedherein including tire pressure and temperature monitors, for example.

Ultra-capacitors are now being developed to replace batteries in laptopcomputers and other consumer electronic devices. They also have a uniquerole to play in tire monitors when energy harvesting systems are usedand generally as replacement for batteries. A key advantage of anultra-capacitor is its insensitivity to high temperatures that candestroy conventional batteries or to low temperatures that cantemporarily render them non-functional. Ultra-capacitors also do notrequire replacement when their energy is exhausted and can be simply berecharged rather than requiring replacement as in the case of batteries.

1.4.4 Communication, RFID

One problem discussed in relevant patents and literature on tiremonitoring is the determination of which tire has what pressure. Avariety of approaches have been suggested in the current assignee'spatents and patent applications including placing an antenna near eachwheel, the use of highly directional antennas (one per wheel butcentrally located), the use of multiple antennas and measuring the timeof arrival or angle of arrival of the pulses and the use of anidentification code, such as a number, that is transmitted along withthe tire pressure and temperature readings. For this latter case, thecombination of an RFID with a SAW TPM is suggested herein. Such acombination RFID and SAW in addition to providing energy to boost theSAW system, as described above, can also provide a tire ID to theinterrogator. The ID portion of the RFID can be a number stored inmemory or it can be in the form of another SAW device. In this case, aPVDF RFID Tag can be used that can be manufactured at low cost.Specifically, the PVDF ID inter-digital transducers (IDTs) can beprinted onto the PVDF material using an ink jet printer, for example, orother printing method and thus create an ID tag at a low cost and removethe need for memory in the RFID electronic circuit.

The SAW-based tire monitor can preferably be mounted in a vertical planeto minimize the effects of centrifugal acceleration. This can beimportant with SAW devices due to the low signal level, unless boosted,and the noise that can be introduced into the system by mechanicalvibrations, for example.

Use of a SAW-based TPM, and particularly a boosted SAW-based TPM asdescribed herein, permits the aftermarket replacement for otherbattery-powered TPM systems, such as those manufactured by Schrader,which are mounted on the tire valves with a battery-less replacementproduct removing the need periodic replacement and solving the disposalproblem.

Although in general, use of a single TPM per tire or wheel is discussedand illustrated above, it is also possible to place two or more suchdevices on a wheel thereby reducing the effect of angular position ofthe wheel on the transmission and reception of the signal. This isespecially useful when passive SAW or RFID devices are used due to theirlimited range. Also, since the cost of such devices is low, the cost ofadding this redundancy is also low.

U.S. Pat. No. 6,581,449 describes the use of an RFID-based TPM as alsodisclosed herein wherein a reader is associated with each tire. In theinvention herein, the added cost associated with multiple interrogators,or multiple antennas connected with coax cable, is replaced with thelower cost solution of a single interrogator and multiple centrallylocated antennas.

The ability to monitor a variety of tires from a single location in oron a vehicle has been discussed above as being important for keeping thecost of the system low. The need to run a wire to each wheel well, andespecially if this wire must be a coax cable, can add substantially tothe installed system cost. One method of increasing the range of RFID isdescribed in Karthaus, U. et al. “Fully integrated passive UHF RFIDtransponder IC with 16.7 microwatt Input Power” IEEE Journal ofSolid-State Circuits, Vol. 38, No. 10, October 2003 and is applicable tothe inventions disclosed herein. Another approach is to make use of theintermittent part of FCC Rule 15 wherein the transmissions per hour arelimited to 2 seconds. In that case, the transmitted power can beincreased substantially which can result in an 80 db gain which can verysubstantially increase the distance permitted from the antenna to theSAW or RFID device. Also, Niekerk describes an extended-range RFID thatis useable with at least one invention disclosed herein as described inU.S. Pat. No. 6,463,798, U.S. Pat. No. 6,571,617 and U.S. patentapplication publication Nos. 20020092346 and 20020092347.

When using an RFID device as described herein, the frequency the RFIDdevice transmits can be different from the frequency used to power thedevice and both can be different from the frequency used by a SAW devicethat may be present. Sometimes a low frequency in the KHz range can beused to pass energy to a tire-mounted device as the device can be in thenear field which can be more efficient for energy transfer. On the otherhand, a directional high frequency transmission, for example in the 900MHz range, may be more efficient for information transfer. Also, FCCrules may permit higher transmit power for some frequencies such asRadar which can make these frequencies better for power transfer.

When a box, for example, contains 100 RFID tags (which may be passivetags), the RFID industry has developed methods to read and write to all100 tags without data collision problems. This is partially due to thedigital nature of the RFID communication protocols. See, for exampleGB2259227, WO9835327, WO0241650, U.S. Pat. No. 3,860,922, U.S. Pat. No.4,471,345, U.S. Pat. No. 5,521,601, U.S. Pat. No. 5,266,925, U.S. Pat.No. 5,550,547, U.S. Pat. No. 5,521,601, U.S. Pat. No. 5,673,037, U.S.Pat. No. 5,515,053, U.S. Pat. No. 6,377,203, and U.S. patent applicationpublication Nos. 20020063622 and 20030001009. When communicating with aSAW device, analogue information is received from each SAW making itmore difficult to separate the transmissions from the four tires using asingle, centrally mounted antenna system. Thus if the signals werepurely RFID-based, then this separation can be achieved but with SAWsystems, even thought they have a greater range than RFID systems, thisseparation is more difficult. Discussions above have addressed thisproblem using smart antennas, multiple antennas and other mechanismsthat use information related to tire rotation etc. Others in theindustry have solved the problem by putting an antenna in each wheelwell which significantly increases the installation costs since thewires to each wheel well should be coax cables. The solution describedbelow is thus a significant breakthrough in this field.

The following discussion is directed to a preferred embodiment of a tirepressure and temperature sensor based on SAW but using a companion RFIDdevice in a novel and unique manner. In this design, sketched in FIG.91, one or more RFID devices 302 each function as, controls or includesa switch 315 that turns on when it receives its appropriate code. Thistechnique is equally applicable to other SAW-based sensors and is notlimited to tire monitors. Each sensor assembly (tire pressure monitor orother) can include an antenna 303 in series with an RFID device302/switch 315 in series with the SAW sensor 304. Each RFID device 302has a programmable address (which may or may not come pre-programmed)and either has within, or can control externally, switch 315 thatconnects or disconnects the SAW sensor 304 from a circuit. Theinterrogator 309 can send either RFID device commands or can send SAWdevice interrogation pulses. RFID commands can be:

<Address> enable switch 315

All sensors disable

When the RFID device 302 receives the enable command from theinterrogator 309, matched to its address, it can close the switch 315and connect the SAW sensor 304 to the receive antenna 303. Theinterrogator 309 will then send a SAW interrogation signal to bereceived by the SAW sensor 304 (which can be part of a preferredpressure sensor) a single pulse and monitor the received transmissionfrom the SAW sensor 304. After the transmission is received, theinterrogator 309 will then send the disable command.

When the RFID device 302 sees the global disable command, it can openthe switch 315, disconnecting the SAW sensor 304 from the circuit withthe receive antenna 303. In this manner, only one SAW sensor 304 willrespond at any given time. This can be advantageous for a tire pressureand temperature device, for example, in that coherent interferencegreatly influences the ability of the interrogator circuitry toaccurately measure phase change, for example. This means that ifmultiple sensors responded at the same time, the accuracy of the systemcan be substantially degraded. Consider the following example:

Input Information:

Radiated power of interrogator to remain within FCCrequirements—P_(burst)=0.5 W;

Radiated frequency—433.92 MHz;

Total losses of a radio signal cycle—50 to 55 dB consisting of;

-   -   IL_(sens.)=−20 dB—sensor losses;    -   IL_(inpt.)=−15-17.5 dB—Losses in transmission from the        interrogator to the sensor;    -   IL_(out.)=−15-17.5 dB—Losses in transmission from the sensor to        the interrogator.

Transponder's antenna impedance—R_(sens.)=75 Ohm.

The pulse amplitude U_(pic.) in the sensor's antenna (input signal) is:Upic.=1.4*√{square root over (Pburs.*ILinpt.*Rsens.)}=1.144-1.525 V

This is consistent with work of Transense Technologies in theirpublished results where they show oscilloscope traces of a 500 mvinterrogator pulse measured at the SAW antenna yielding a larger than 1volt pulse in the SAW circuit as shown in FIG. 51.

An example of the electric circuit for such transponder is shown in FIG.52A.

An oscillogram of RF pulses, which are radiated by the interrogator, areillustrated in FIG. 53.

The transponder's antenna is connected to two diode detectors, D1 andD2, which transpose the signal from the antenna to create a supplyvoltage (approximately 1.2V) for the digital code analyzer DK1 andsensor's SPDT switch S1 as shown in FIG. 54. FIG. 55 illustrated theoutput from diode detectors D3 and D4 which transpose signals from theantenna to digital code.

If the code sequence from the interrogator corresponds to an individualcode of the given sensor, the digital code analyzer causes a switch tobe turned on. In the illustrated example, the code sequence consists oftwo pulses. The number of pulses can of course be increased and, asdiscussed below, a 32 or 64 bit switch is contemplated for someimplementations.

Generally, the pulse duration of the power excitation and call lettersignals can be 70 to 80 microseconds as shown. During this time period,the supply voltage is relatively constant and the sensor is notconnected to the antenna. Thus there are no echo pulses excited in thesensor.

If the code sequence is correct and a turn-on voltage for the switch isreceived, the sensor is connected to the antenna. This state remains fora long time such as hundreds of microseconds. The SAW sensor is thusready to measure the temperature and pressure. After sensing aninterrogation pulse to the SAW sensor, it is necessary to pause beforefor approximately 20 microseconds (in this case) before sending a newinterrogating pulse. This pause is necessary in order to let the echopulses which still remain from the previous interrogating pulse to dieout or dissipate. Thus, it is possible to execute sequentially 10 to 30cycles of independent measurements since the retention time of a supplyvoltage is 300 to 500 microseconds.

A sensor can be disconnected from the antenna for one of two reasons:

-   -   1. When a special code sequence is received, the turn off all        sensors code. This code sequence is the same for all sensors.    -   2. If the supply voltages has decreased below a threshold and no        pulses come from the antenna which can happen, for example, when        the vehicle is parked. In the illustrated example, this will        happen in approximately 10 milliseconds.

Modeling of the circuit design has been done with the “CircuitMaker2000” software package. It was assumed that a special microcircuit chipwith a 1 to 1.5 V supply voltage and approximately a 10 microamperecurrent mode is used. It conforms to the equivalent resistance which isconnected to power supply, 10K. Such microcircuit chips are used inelectronic watches and micro calculators. Note that for a particulardesign if the supply voltage proves insufficient, it is possible to usediode voltage multipliers (in the circuit's schematic, a doubling diodedetector is shown).

The above discussion assumes that the interrogator knows the switch IDfor each wheel or other such device on the vehicle. Initially or after atire rotation, for example, or the addition of additional similardevices, the vehicle interrogator will not know the switch IDs and thusa general method is required to teach the interrogator this information.Many schemes exist or can be developed to accomplish this goal. Each ofthe devices can be manually activated, for example, under aninterrogator learning mode or through the use of a manual switch on eachtire. An alternate and preferred method is to have this accomplishedautomatically as in plug-and-play. One way of accomplishing this willnow be described but this invention is not limited to this particularmethod and encompasses any and all methods of automatically locating anRFID, SAW or similar sensing device including tire temperature andpressure monitors, other temperature, liquid level, switch, chemicaletc. sensors as discussed anywhere else herein and other similar typedevices that are not discussed herein. See also, for example, U.S. Pat.No. 6,577,238.

In a preferred implementation, each device is also provided with aconventional RFID tag which can be read with a general command in asimilar method as conventional RFID tags. These tags may operate at adifferent frequency than the RFID switch discussed above. The RFID tagassociated with a particular device will have either the same code asthe RFID switch or one where the switch code is derivable from the tagcode. The interrogator on key on, or at some other convenient time, willinterrogate all RFID tags that are resident on the vehicle and recordthe returned identification numbers. During this process it will alsodetermine the location of each tag based on time of flight, time ofarrival at different elements of an antenna array, angle of arrival,coefficients of a smart antenna (such as Motia), or any other similarmethod. This is possible since the tags will be sending digitalinformation according to a fixed protocol. This can be much moredifficult to achieve with analogue data sent by a SAW transponder orsensor where the exact format can depend on the value of themeasurements being made. Thus, by this method, the interrogator candetermine the ID of the RFID switch and its location in a simple manner.Since this is a very infrequent event and in fact the interrogator canbe designed to only conduct this polling operation once per hour or evenno more than once per day, the power that can be transmitted by theinterrogator can be the maximum allowable for the chosen frequency bythe FCC. RFID readers can now read tags at a distance exceeding 3meters, for example, can sort out 100 or more tags simultaneously. Note,that by using this method, the high power that is only intermittentlyallowed by FCC regulations is only needed to determine what devices areon the vehicle and where they are located. After this is known, a muchlower power operation is used for switching the RFID switch andinterrogating the SAW sensor.

The switching component that accompanies the RFID switch can be a FET,MEMS, PIN diode or CMOS device or equivalent (see, e.g., Prophet, G“MEMS flex their tiny muscles” pp. 63-72, EDN Magazine, Feb. 7, 2002).RF switches are designed to switch Radio Frequency signals, usually fromthe antenna. They must have low losses and be able to match theimpedances to keep the standing ware ratio low. Some are designed toswitch specific impedances e.g. 50 ohm, or 75 ohms and others are wideband and can switch from DC to GH signals. The three common types are:

1. MEMS which are mechanical. Wide band, low loss, can switch watts andrequires milliwatts of Power to operate. The switching speed is in themicrosecond to milliseconds range. One example switches in microsecondsand requires (5 volts @ 1 ma) 5 mw DC power to operate. Others existwith lower switching voltage and power.

2. PIN Diode switches. Wide band, medium switching loss, switches wattsand requires low power to operate. The switching speed is fast. Some aredesigned for specific impedances e.g. 50 ohm etc.

3. GaAs FET. These provide very fast switching with medium switchinglosses, microwatts of power are required to switch. Some require dualsupply voltages to control switch.

The RF switch switches on and off the sensor which can be a SAW sensorto the antenna under control of a signal that comes from identificationdevice. Desirable properties of the RF switch are:

-   -   Minimal level of required control voltage (1V-2V is preferred);    -   Minimal current consumption (less then 1 microampere is        preferred);    -   High off isolation (should be not less then 30 dB) when drive        signal is absent on control input pins;

Two types of RF switches have been tested for use in transponders. Theyare: ADG936BRU (absorptive) and ADG936BRU-R (reflective) ICs from AnalogDevices (See specifications of RF-switches ADG936BRU H ADG936BRU-R fromAnalog Devices).

FIG. 52B illustrates an electronic circuit that can be used with theRFID switch discussed above and FIG. 52C illustrates an example of itstiming diagram. The circuit operates as follows. The interrogator (notshown) transmits a high power RF pulse train which is received by allsensors. The power pulse is rectified by PIN diode circuits D1 and D2charging Capacitors C3 and C4. This is the power source for thetransponder. The voltage TPN to TPP is the supply voltage. The ID codeis shown at TPB, this is the input to the comparator in themicroprocessor. The microprocessor decodes the signal, the one and onlyone which has the matching Code will switch the CMOS switch U2connecting the antenna to the SAW device which will respond. Note thenormal interrogator pulses follow the ID code and are not shown on theabove timing diagram.

All sensors not having the sent code will immediately go to sleep at theend of the ID code, only the one with matching code will switch its U2CMOS switch. The microprocessor with the matching code will turn off U2and go to sleep at the end of the SAW sensor's response. Since all SAWsensors receive the Power UP and ID code signal, all sensors will remainpowered up at normal interrogation times. If there is a long timebetween interrogations, the Power UP and ID code will put all sensors inoperation.

It is also proposed that an output from the microprocessor be madeavailable so that, before the sensor is installed or put into the tirein the case of the TPM, the interrogator can read and store the ID codefor the unit. This would eliminate the housekeeping chore of keepingtrack of codes. Each sensor will have a unique ID number, for a 64 bitcode there are 1.8447×E19 codes available. That's about 4 k codes pereach person in the world.

Power can also be supplied by a PZT circuit, or other energy harvestingmethod as discussed herein, which can generate voltage for anultracapacitor by the motion of the tire. The microprocessor willoperate with a supply voltage from 2.2 to 3.6 volts. There are othersthat will operate below this level but the selected CMOS switch won'toperate below about 2.2 volts. The MSP430F is a low cost 16 bitmicroprocessor from Texas Instruments. The above assumes a Pburst of atleast 0.5 Watts from the interrogator as per FIG. 51.

This universal concept can now be used for all situations where a deviceis to be turned on wirelessly when the ID code is not initially known.This concept can be used with RFID tags that operate at any frequencyfrom 12 KHz to 24 GHz and beyond. It can be at the same frequency as theRFID switch or at a different frequency. If the same frequency is usedthen the switch code can be different but derivable from the RFID tag.For example, the tag code can always be an odd number and the switchcode equal the tag code plus 1. Any code length can be used but thepreferred code length is 32 bits since it provides 4.3 billion uniquecodes which is sufficient for dozens of devices per vehicle.

The above discussion has covered SAW transponders and RFID transpondersand the combination of an RFID switch with SAW and RFID tagtransponders. RFID tags can send data as well as their ID. The SAWdevice, however, provides an analogue output which in general isinterpreted by the interrogator to determine the tire pressure andtemperature, for example. The incorporation of a typical analogue todigital converter generally requires more power than is readilyavailable in the systems that have been described herein. However, theSAW device can and does in some of the above TPM examples provide aseries of pulses that relate to the temperature and pressure, forexample, that can also be interpreted as digital codes. These codes,with appropriate circuitry, can be converted into bits of data andcommunicated by an RFID tag thus eliminating the need to send data tothe SAW from the interrogator. This also eliminates the need for theRFID switch. The drawback of such a system is that now the powersufficient to operate an RFID tag at a distance of two or more meterscan exceed the limitations of Rule 15 of the FCC regulations whichallows an occasional high powered transmission but not a continuousperiodic transmission. However, this problem can disappear withimprovements in circuitry and/or changes in or special exceptionsallowed to the FCC rules.

In addition to SAW devices for temperature and pressure measurement,other low power devices exist such as capacitive, inductive orresistive-based temperature and pressure sensors and their use inconjunction with an RFID tag is contemplated by the invention disclosedherein. For a similar application of a combined passive RFID tag and asensor see D. Watters “Wireless Sensors Will Monitor Bridge Decks”,Better Roads Magazine, February 2003. Previously, combined RFID tags andsensors that are passive have not been used on vehicles for tiretemperature and pressure monitoring or for any other purpose. With theexception of the bridge deck monitor, when sensors have been used withpassive RFID tags, only the tag has obtained its power from the RFsignal while the sensor has been separately battery or otherwise powered(see, e.g., U.S. Pat. No. 6,377,203).

An alternate SAW based tire pressure and temperature monitor isillustrated in FIGS. 90A and 90B. This design uses a very low powercircuit such that the power can be supplied by radio frequency in thesame way that RFID tags are powered. Alternately the power can besupplied by an energy harvesting device or even a very long life batteryor ultracapacitor. A block diagram is shown in FIG. 90A where:

Oscillator A can be either a delay line or resonator depending on howthe sensor, for example a SAW, is used.

Oscillator B can be either a delay line or resonator depending on howthe sensor, for example a SAW, is used.

F1 is the frequency which is determined by the sensor, for example theSAW.

F2 is the frequency which is determined by F1 but also varies withtemperature.

F3 is the frequency which is determined by F1 but also varies withtemperature and pressure.

1 is a signal point in FIG. 90A at the mixer A output and is equal to(F2+F1)+(F2−F1)

4 is a signal point in FIG. 90A at the mixer A after filtering outputand is equal (F2−F1) which is a function of temperature.

2 is a signal point in FIG. 90A at the mixer B output and is equalto=(F3+F2)+(F3−F2)

3 a signal point in FIG. 90A at the mixer B after filtering output andis equal (F3−F2) which is a function of temperature.

The microprocessor measures frequency 3 and 4 by counting. It alsostores a 32, for example, bit ID codes and the pressure and temperaturecalibration constants.

The operation is as follows. The Oscillator A and Oscillator B may bedelay line oscillators or resonator oscillators. The SAW device isconnected to low power Oscillator A and Oscillator B. The SAW determinesthe frequency of the Oscillator A and Oscillator B. The frequency, F2 ofOscillator A, changes with temperature. The frequency, F3 of OscillatorB, changes with temperature and with pressure. The frequency F1 (CrystalControlled) for the microprocessor is stable with temperature. Mixer(MIX A) multiplies F2 and F1 giving an output of (F2+F1) and (F2−F1),the LP Filter (low pass filter) eliminates the (F2+F1) frequency leavingthe output at 4 of (F2−F1) which is a function of the temperature. Thetemperature function is measured by counting with the microprocessor.The scale factor correction (stored in the microprocessor) sets thescale for temperature. The value is a digital number stored in themicroprocessor.

Mixer (MIX B) multiplies frequencies F2 and F3 having an output of(F3+F2) and (F3−F2), the low pass filter (LP Filter) removes the(frequency (F3+F2) leaving the output at 3 of (F3−F2) which is theF(PSI) which is measured by the microprocessor by counting. The scalefactor correction for PSI is stored in the microprocessor at calibrationtime. The resulting output is the corrected PSI which is stored in themicroprocessor. The microprocessor controls an RF transmitter whichtransmits the ID (identification code) of the unit along withtemperature and pressure to the receiver. The transmission is pseudorandom. Between readings, the RF transmitter is OFF, and themicroprocessor is in the sleep mode so that the average power is verylow.

There is a connection to the microprocessor for calibration. Atmanufacture, the ID code typically 32 bits is stored in themicroprocessor. Controlled temperature and pressure is applied to theunit, scale factors are determined and stored in the microprocessor.This allows for variation in SAW devices to be compensated. Before theunit is put into operation (into a tire etc.) the unit is plugged intothe display unit which reads and stored the ID code. This is done usingthe Cal and install connector.

The central unit, the Display unit has an RF receiver which listens fora response, it reads the ID code, checks the ID against its stored codesand if the code agrees displays the readings. If two codes arrive at thesame time, they are disregarded and since the units talk at random thenext readings will arrive at different times and there will be nocontention. The transmitter sends the ID and data at frequency F(x)which is totally independent of the frequency of the SAW device. Thetransmitted signal is more tolerant to noise since the signaltransmitted is digital and not low level analog. Also the transmittedpath is one way so signal losses are lower. All components except theSAW are low power and low cost CMOS parts. Power is supplied circuit 2at a frequency independent of the F(x) frequency.

1.4.5 Exterior Tire Temperature Monitor

An externally-mounted tire temperature sensor will now be discussed.FIG. 56 illustrates a tire temperature sensor that is not mounted on thetire in accordance with an embodiment of one of the inventions herein.The tire temperature sensor 265 is mounted on the vehicle in a positionto receive thermal radiation from the tire 266, e.g., situated in a tirewell 267 of the vehicle. Each tire well of the vehicle can include oneor more temperature sensors 265. If more than one tire is present in awell, e.g., on trucks, then the placement of a plurality of sensorswould be advantageous for the reasons discussed below.

As shown in FIG. 56A, temperature sensor 265 includes a temperaturemeasuring component 265A, a power supplying/temperature measurementinitiating component 265B coupled to the temperature measuring component265A and a temperature transmission component 265C also coupled to thetemperature measuring component 265A.

Temperature measuring component 265A may be a transducer capable ofmeasuring temperature within about 0.25 degrees (Centigrade). Thisbecomes a very sensitive measure, therefore, of the temperature of thetire if the measuring component 265A is placed where it has a clear viewof the tire tread or sidewall, i.e., the tire is in the field of view ofthe measuring component 265A. The status of a tire, for example whetherit is worn and needs to be replaced, damaged or operating normally, canthen be determined in a processor or central control module 268 bycomparing it to one or more mating tires on the vehicle. In the case ofa truck trailer, the mating tire would typically be the adjacent tire onthe same axle. In an automobile, the mating tire could be the other tireat the front or back of the vehicle. Thus, for a sport utility vehicle(SUV), the temperature of the two rear tires of the SUV can be comparedand if one is hotter than the other than it can be assumed that if thistemperature differential persists that the hotter tire isunder-inflated, delaminating, has a damaged carcass or is otherwisedefective.

Temperature measuring component 265A will usually require power toenable it to function. Power is therefore supplied by the powersupplying/temperature measurement initiating component 265B which may bein the form of appropriate circuitry. When inductively powering sensor265, power supplying component 265B is located proximate the pair ofparallel wires carrying high frequency alternating current through thevehicle and is designed to receive power inductively from the pair ofwires. Communication with sensor 265 could be over the same pair ofparallel wires, i.e., a single bus on the vehicle provides bothcommunications and power, and sensor 265 would have a dedicated addressto enable communication only with sensor 265 when desired. This conceptis discussed, for example, in U.S. Pat. No. 6,326,704 and elsewhereherein. Power supplying component 265B can also be designed to beactivated upon the transmission of radio frequency energy of a specificfrequency. Thus, when such radio frequency energy is transmitted, powersupplying component 265B is activated and provides sufficient power tothe temperature measuring component 265A to conduct a measurement of thetemperature of the tire and enable the transmission of the detectedtemperature to a processor or central control module of the vehicle viatemperature transmission component 265C.

Power supplying component 265B can also be integrated with a battery inthe event that the circuitry for receiving power inductively or throughradio frequency energy is inoperable.

An electric circuit for inductively receiving power and an electriccircuit for supplying power upon being activated upon transmission of acertain radio frequency are well-known in the art and can be any ofthose in the prior art or any improvements thereto. Also, the powersupplying component 265B can be any component which is designed toreceive power (electricity) wirelessly or receive an activation signalwirelessly or by wire.

The processor 268 is mounted in the vehicle and includes any necessarycircuitry and components to perform the reception function, i.e., thereception of the transmitted temperature from the temperaturetransmission component 265C of each sensor 265, and the comparisonfunction, i.e., to compare mated tires, or to compare the temperature ofthe tire to a threshold. The reception function may be performed by areceiver 269 mounted in connection with the processor 268.

The threshold to which the temperature of the tire is compared may be apredetermined threshold value for the specific tire, or it may bevariable depending on the vehicle on which the tire is mounted. Forexample, it may depend on the weight of the vehicle, either in itsunloaded state or in its loaded state. It could also vary based on thedriving conditions, weather conditions or a combination of thepreviously mentioned factors.

Upon the processor 268 making such a determination based on thecomparison of the data obtained from two tire temperature sensors, itcan activate or direct the activation of a responsive system to alertthe driver by displaying a warning light, sound an audible alarm oractivate another type of alarm or warning system. A display can also beprovided to display, e.g., to the vehicle occupant, an indication orrepresentation of the determination by the processor. In general, such adisplay, alarm or warning device will be considered a response unit orresponsive system. Another response unit may be a telecommunicationsunit which is operative to notify a vehicle service facility of the needto inflate one or more of the tires, or repair or replace one or more ofthe tires. In this regard, the invention can be integrated orincorporated into a remote vehicle diagnostic system as disclosed inU.S. Pat. No. 5,684,701 to the current assignee.

The tire temperature sensor 265 can also be used to warn of a potentialdelamination, as have occurred on many tires manufactured by Firestone.Long before the delamination causes a catastrophic tire failure, thetire begins to heat and this differential temperature can be measured bythe tire temperature sensor 265 and used to warn the driver of a pendingproblem (via the response unit). Similarly, the delamination thataccompanies retreaded tires on large trucks even when they are properlyinflated can be predicted if the temperature of the tread of the vehicleis monitored. The more common problem of carcass failure from any causecan also be detected as either the defective tire or its mate, in thecase of paired tires, will exhibit a temperature increase beforeultimate failure occurs. The output of the tire temperature monitors canalso be recorded so that if a warning went unheeded by the driver, he orshe can be later held accountable. With the large quantity of tiredebris littering roadways and the resulting accidents, a monitor,recording and warning system such as described herein which caneliminate this hazard may very well be mandated by governmentalauthorities.

One disadvantage of an external temperature measuring system is that itcan be prone to being occluded by snow, ice, and dirt. This problem isparticularly troublesome when a single external sensor is used but wouldbe alleviated if multiple external sensors are used such as shown inFIG. 56. An alternate approach is to place a temperature sensor withinthe vehicle tire as with the pressure sensor, as described above. Theresulting temperature measurement data can be then transmitted to thevehicle either inductively or by radio frequency, or other similarsuitable method. A diagnostic system can be provided to inform thedriver of a malfunctioning monitor. Such a diagnostic system can includea source of IR radiation that would irradiate a tire as a test fordetection by the monitor.

In accordance with the invention, it is therefore possible to use bothtypes of sensors, i.e., an externally-mounted sensor (external to thetire) and an internally-mounted tire, i.e., a sensor mounted inconnection with the tire. FIG. 56 thus shows a sensor 270 is placedwithin the tire 266 for those situations in which it is desirable toactually measure the pressure or temperature within a tire (or for whenthe external sensor 265 is occluded). Sensor 270 can be designed tomeasure the temperature of the air within the tire, the temperature ofthe tire tread and/or the pressure of the air in the tire. Sensor 270can be any of those described above.

Preferably, sensor 270 receives its operational power either inductivelyor through radio frequency. Previously, inductively-powered tire-mountedsensors have taken place at very low frequencies, e.g., about 100 Hz,and no attempt has been made to specifically design the inductive pickupso that the efficiency of power transfer is high. In contrast, thepresent invention operates at much higher frequencies, in some cases ashigh as 10 kHz or higher, and approaches 99 percent efficiency.Additionally, many systems have attempted to transmit tire pressure tothe vehicle cab wirelessly with poor results due to the interveningmetal surfaces of the vehicle. A preferred approach in the presentinvention is to transmit the information over the inductive power sourcewires.

FIGS. 57A and 57B show an embodiment for detecting a difference intemperature between two tires situated alongside one another, forexample on a truck trailer. A difference in temperature between twotires operating alongside one another may be indicative of a pressureloss in one tire since if the tires are not inflated to the samepressure, the tire at the higher pressure will invariably carry moreload than the under-inflated tire and therefore, the temperature of thetire at the higher pressure will be higher than the temperature of theunder-inflated tire. It can also predict if one tire is delaminating.

In this embodiment, the tire temperature/pressure measuring system 274includes a thermal emitted radiation detector 275, a Fresnel lens 276 inspaced relationship from the thermal emitted radiation detector 275 anda shutter 277 arranged between the thermal emitted radiation detector275 and the Fresnel lens 276. The Fresnel lens 276 includes lenselements equal in number to the number of tires 280,281 situatedalongside one another, two in the illustrated embodiment (lens elements278,279). Each lens elements 278 and 279 defines a field of view for thedetector 275 corresponding to the associated tire 280,281. The shutter277 is operated between a first position 283, and is biased toward thatposition by a return spring 284, and a second position 285 and isattracted toward that second position by an electromagnet 286. In thefirst position 283, the shutter 277 blocks the field of view from thelens element 279 corresponding to tire 281 and allows the field of viewfrom the lens element 278 corresponding to the tire 281. In the secondposition 285, on energizing electromagnet 286, the shutter 277 blocksthe field of view from the lens element 278 and allows the fields ofview from lens element 279. As the detector 275 is sensitive to changesin temperature, the switching between fields of view from one tire tothe other tire will provide a difference if the temperature of one tirediffers from the temperature of the other.

Referring to FIG. 57B, the detector 275 establishes fields of view 287and 288 generally directed toward the tires 280,281, respectively. Thefields of view 287 and 288 correspond to the Fresnel lens elements 278and 279, respectively. The thermal emitted radiation detector 275, forthe 8-14 micron range, may be a single element pyroelectric detectorsuch as the Hamamatsu P4736. As an alternative, a pyroelectric detectorhaving two sensing elements, for example, a Hynman LAH958 may be usedwith one of the detecting elements covered. Alternatively, a semi customdevice could be used. Such devices are usually manufactured with a largeresistor, e.g., 100 GOhm, in parallel to the detecting elements. A lowervalue of this resistor provides a wider effective bandwidth with atradeoff of less sensitivity at lower frequencies. If a lower frequencycutoff of about 10 Hz is desired, a resistor value of about 100 MOhmwould be appropriate. These types of pyroelectric detectors aresensitive to changes in temperature and not to absolute temperature,thus the detector must see a change in temperature in order to generatean output signal. This change in temperature will occur when one tire isat a higher or lower pressure than the adjacent tire indicatingunder-inflation of one of the tires, a failing carcass or isdelaminating. The measurement of the change in temperature between thetires may be accomplished by a shutter mechanism as described above. Theshutter could be driven at a constant rate of about 10 Hz. The rate ofoperation must be slow enough to come within the band pass of thepyroelectric detector used. The preceding and following discussions weretaken largely from U.S. Pat. No. 5,668,549 where a more detaileddiscussion of the operation of pyroelectric detectors can be found.

FIG. 58 illustrates a Fresnel lens 276 in accordance with one embodimentof the present invention. The Fresnel lens 276 includes lens elements278 and 279 which are aligned with the tires 280,281. The lens elements278 and 279 are offset from each other to provide different fields ofview, as illustrated in FIG. 57B. The Fresnel lens 276 also includes athermal emitted radiation opaque mask 289 around the lens areas. Thelens elements 278 and 279 are dimensioned to ensure that the thermalemitted radiation collected by the lens elements 278,279 when thepressure of the tires is substantially the same will be the same, thatis, no temperature difference will be detected.

Referring to FIG. 59, a circuit for driving the shutter mechanism andfor driving from the detector to provide an indication of a temperaturedifference between a mated pair of tires situated alongside one anotheris shown. In this non-limiting embodiment, the circuit includes adetector circuit 293 providing input to an amplifier circuit 294 whichprovides input to a demodulator circuit 295 which provides input to anenunciator circuit 296. The demodulator circuit 295 is driven by a 10 Hzsquare wave generator 297 which also drives the shutter electromagnet292. The detector circuit 293 includes the pyroelectric detector. Outputfrom the detector is capacitively coupled via capacitor C1 to theamplifier circuit 293 provided with two amplification stages 298 and299. The amplifier circuit 294 acts as a high pass filter with a cut offfrequency of about 10 Hz. The output of the amplifier circuit 294 isapplied as input to the demodulator circuit 295. The demodulator circuit295 is operated at a frequency of 10 Hz by applying the output of the 10Hz square wave generator 297 to switches within the modulator circuit.The enunciator circuit 296 has comparators 300 and 301 which compare theoutput of the demodulator circuit 295 to threshold values to determine atemperature difference between the mated tires above a threshold valueand in response, e.g., provides an output indication in the form of adrive signal to an LED D3.

FIGS. 60-62 illustrate alternative embodiments of the thermal emittedradiation detector 274. In the preferred embodiment of FIGS. 57A and57B, the reference fields of view of the tires 280, 281 are defined byFresnel lens elements 278 and 279, respectively, with selection of thefield of view being determined by the shutter 277. It is possible toprovide various mechanical shutter arrangements, for example vibratingreeds or rotating blades. A LCD used as a shutter can work with thermalemitted radiation. It is also possible to change the field of view ofthe detector 275 by other means as described below.

Referring to FIG. 60, a single Fresnel lens 305 is provided andsupported at one side by a vibrating device 306. Other types of lensescan be used. The vibrating device 306 may be electromechanical orpiezoelectric in nature. On application of the drive signal to thevibrating device 306, the Fresnel lens 305 can be rocked between twopositions, corresponding to a field of view of tire 280 and a field ofview of tire 281. As the detector 275 is sensitive to change intemperature, the change in fields of view results in an output signalbeing generated when there is a difference in temperature between tires280 and 281. Operation of the rest of the detector is as described withregard to the preferred embodiment. As is well known in the art, theoptical elements lenses and the optical elements mirrors may beinterchanged. The Fresnel lens of FIG. 60 may thus be replaced by aconcave mirror or other type of lens.

FIG. 61 illustrates such an arrangement in another embodiment of theinvention. In this embodiment, the Fresnel lens 305, of FIG. 60, isreplaced by a concave mirror 307. The mirror 307 is mounted in a similarmanner to the Fresnel lens, and in operation vibrates between two fieldsof view.

The embodiment of FIG. 62 uses fixed optics 308, i.e., a lens or amirror, but imparts relative movement to the detector to define twofields of view. While the embodiments of FIGS. 60-62 have been describedusing the square wave generator of a preferred embodiment of FIGS. 57Aand 57B, other waveforms are possible. The embodiments of FIGS. 60-62define fields of view based on relative position and would capable ofcontinuous movement between positions if the detector has sufficientbandwidth. For example, either an MCT (HgCdTe) detector or apyroelectric with a relatively low parallel resistor (about 1 MOhm)would have sufficient bandwidth. A saw-tooth waveform could thus be usedto drive the vibration device 306 to cause the field of view to sweep anarea covering both tires 280,281.

Instead of using the devices shown in FIGS. 57A, 57B and 60-62 fordetermining a temperature difference between mated tires, it is possibleto substitute a heat generating or radiating element (as a referencesource) for one of the tires whereby the heat generating element isheated to a predetermined temperature which should equal the temperatureof a normally operating tire, or possibly the temperature of a tire inthe same driving conditions, weather conditions, vehicle loadingconditions, etc. (i.e., the temperature can be varied depending on theinstantaneous use of the tire). Thus, the field of view would be of asingle tire and the heat generating element. Any difference between thetemperature of the heat generating element and the tire in excess of apredetermined amount would be indicative of, e.g., an under-inflatedtire or an over-loaded tire. In this method, the sensor detects theabsolute temperature of the tire rather than the relative temperature.It is also possible to construct the circuit using two detectors, onealways looking at the reference source and the other at a tire andthereby eliminate the need for a moving mirror or lens etc.

FIG. 63 shows a schematic illustration of the system in accordance withthe invention. Power receiving/supplying circuitry/component 310 is thatportion of the arrangement which supplies electricity to the thermalradiation detectors 311, e.g., the appropriate circuitry for wired powerconnection, inductive reception of power or radio frequency energytransfer. Detectors 311 are the temperature sensors which measure, forexample, the temperature of the tire tread or sidewall. For example,detector 311 may be the thermal emitted radiation detecting devicedescribed with reference to FIGS. 56, 57A and 57B. Amplifiers and/orsignal conditioning circuitry 312 are preferably provided to conditionthe signals provided by the detectors 311 indicative of the measuredtemperature. The signals are then forwarded to a comparator 313 for acomparison in order to determine whether the temperature of the tiretreads for mating tires differs by a predetermined amount. Comparator313 may be resident or part of a microprocessor or other type ofautomated processing device. The temperature difference which would beindicative of a problem with one of the tires is obtained throughanalysis and investigation prior to manufacturing of the system andconstruction of the system. Comparator 313 provides a signal if thedifference is equal to or above the predetermined amount. Awarning/alarm device 314 or other responsive system is coupled to thecomparator 313 and acts upon the signal provided by the comparator 313indicative of a temperature difference between the mating tires which isgreater than or equal to the predetermined amount. The amplifiers andsignal conditioning circuitry 314 may be associated with the detectors311, i.e., at the same location, or associated with the processor withinwhich the comparator 313 is resident.

FIG. 64 shows a schematic illustration of the process for monitoringtire pressure in accordance with the invention. At step 318, power isprovided wirelessly to a power supplying component associated with thethermal radiation detecting devices. At step 319, the thermal detectingdevices are activated upon the reception of power by the power supplyingcomponent. At step 320, the thermal radiation from the tires is detectedat a location external of and apart from the tires. The thermalradiation for mating tires is compared at step 321 and a determinationmade if the thermal radiation for mating tires differs by apredetermined amount at step 322. If so, an alarm will sound, a warningwill be displayed to the driver and/or a vehicle service facility willbe notified at step 323. If not, the process will continue withadditional detections of thermal radiation from the tire(s) andcomparisons.

Instead of designating mating tires and performing a comparison betweenthe mated tires, the invention also encompasses determining the absolutetemperature of the tires and analyzing the determined absolutetemperatures relative to a fixed or variable threshold. This embodimentis shown schematically in FIG. 65. At step 324, power is providedwirelessly (alternately wires can be used) to a power supplyingcomponent associated with the thermal radiation detecting devices. Atstep 325, the thermal detecting devices are activated upon the receptionof power by the power supplying component. At step 326, the thermalradiation from the tires is detected at a location external of and apartfrom the tires. The thermal radiation for each tire is analyzed relativeto a fixed or variable threshold at step 327 and a determination is madebased on the analysis of the thermal radiation for each tire relative tothe threshold at step 328 as to whether the tire is experiencing aproblem or is about to experience a problem, e.g., carcass failure,delaminating, running out of air, etc. The analysis may entail acomparison of the temperature, or a representation thereof, to thethreshold, e.g., whether the temperature differs from the threshold by apredetermined amount. If so, an alarm will sound, a warning will bedisplayed to the driver and/or a vehicle service facility will benotified at step 329. If not, the process will continue with additionaldetections of thermal radiation from the tire(s) and analysis.

As noted above, the analysis may be a simple comparison of thedetermined absolute temperatures to the threshold. In this case, thethermal radiation detecting system, e.g., infrared radiation receivers,may also arranged external of and apart from the tires for detecting thetemperature of the tires and a processor is coupled to the thermalradiation detecting system for receiving the detected temperature of thetires and analyze the detected temperature of the tires relative to athreshold. The infrared radiation receivers may be arranged in anylocation which affords a view of the tires. A response system is coupledto the processor and responds to the analysis of the detectedtemperature of the tires relative to the threshold. The response systemmay comprise an alarm for emitting noise into the passenger compartment,a display for displaying an indication or representation of the detectedtemperature or analysis thereof, a warning light for emitting light intothe passenger compartment from a specific location and/or atelecommunications unit for sending a signal to a remote vehicle servicefacility.

Referring now to FIG. 66, in this embodiment, instead of comparing thetemperature of one tire to the temperature of another tire or to athreshold, the temperature of a single tire at several circumferentiallocations is detected or determined and then the detected temperaturesare compared to one another or to a threshold.

As shown in FIG. 66, a tire temperature detector 330, which may be anyof those disclosed herein and in the prior art, detects the temperatureof the tire 331 at the circumferential location designated A when thetire 331 is in the position shown. As the tire 331 rotates, othercircumferential locations are brought into the detecting range of thedetector 330 and the temperature of the tire 331 at those locations isthen determined. In this manner, as the tire 331 completes one rotation,the temperature at all designated locations A-H is detected. The tiretemperature detector 330 can also be designed to detect the temperatureof a plurality of different circumferential locations, i.e., havemultiple fields of view each encompassing one or more differentcircumferential locations. Two or more tire temperature detectors 330could also be provided, all situated in the tire well around the tire331.

The temperatures obtained by the tire temperature detector 330, such asthose in the table in FIG. 67, are then analyzed, for example, todetermine variations or differences between one another. An excessivehigh temperature at one location, i.e., a hot spot, may be indicative ofthe tire 331 being in the process of delamination or of the carcassfailing. By detecting the high temperature at that location prior to thedelamination, the delamination could be prevented if the tire 331 isremoved or fixed.

The analysis to determine a hot spot may be a simple analysis ofcomparing each temperature to an average temperature or to a threshold.In FIG. 67, the average temperature is 61° so that the temperature atlocation F varies from the average by 14°, in comparison to a 1°variation from the average for other locations. As such, location F is arelative hot spot and may portend delamination or carcass failure. Theexistence of the hot spot at location F may be conveyed to the drivervia a display, or to a remote vehicle maintenance facility, or in any ofthe other methods described above for notifying someone or somethingabout a problem with a tire. The number of degrees above the average fora location to be considered a hot spot may be determined by experimentalresults or theoretical analysis.

Instead of using the average temperature, the difference between thetemperature at each circumferential location and the temperature at theother circumferential locations is determined and this difference isanalyzed relative to a threshold. For the temperatures set forth in FIG.67, the variation between the temperatures range from about 0-14°. Aprocessor can be designed to activate a warning system when anyvariation of the temperature at any two locations is above 10°. Usingthis criterion, again, location F would be considered a hot spot. Thethreshold variation can be determined based on experimental results ortheoretical analysis.

As also shown in FIG. 67, a threshold of 70° is determined as a boundarybetween a normal operating temperature of a tire and an abnormaloperating temperature possibly indicative of delamination. Thetemperature of the tire 331 at each circumferential location is comparedto the threshold, e.g., in a processor, and it is found that thetemperature at location F is above the threshold. This fact is againprovided to the driver, remote facility, etc. to enable repair orreplacement of the tire 331 prior to actual delamination or otherfailure.

Additional details about the construction, operation and use of thetechnique for measuring the temperature and pressure of a tire and thedesign of sensors capable of being positioned to measure the temperatureof the tire can be found in Appendices 1-5 of the '139 application.

The thermal radiation detecting system may be provided with power andinformation in any of the ways discussed above, e.g., via a powerreceiving system which receive power by wires or wirelessly(inductively, through radio frequency energy transfer techniques and/orcapacitively) and supply power to the thermal radiation detectingsystem. Further, the thermal radiation detecting system can be coupledto the processor. This may involve a transmitter mounted in connectionwith the thermal radiation detecting system and a receiver mounted inconnection with or integrated into the processor such that the detectedtemperature of the tires is transmitted wirelessly from the thermalradiation detecting system to the processor.

In a similar manner, a method for monitoring tires mounted to a vehiclecomprises the steps of detecting the temperature of the tires fromlocations external of and apart from the tires, analyzing the detectedtemperature of the tires relative to a threshold, and responding to theanalysis of the detected temperature of the tires relative to thethreshold. The temperature of the tires is detected by one or morethermal radiation detecting devices and power may be supplied wirelesslyto the thermal radiation detecting device(s), e.g., inductively, throughradio frequency energy transfer, capacitively.

The threshold may be a set temperature or a value relating to a settemperature. Also, the threshold may be fixed or variable based on forexample, the environment in which the tires are situated, the vehicle onwhich the tire is situated, and the load of the vehicle on the tires. Asnoted above, the thermal radiation detecting devices may be wirelesslycoupled to the processor central control module of the vehicle andadapted to receive power inductively, capacitively or through radiofrequency energy transfer.

Thus, disclosed above is a vehicle including an arrangement formonitoring tires in accordance with the invention comprises a thermalradiation detecting system arranged external of and apart from the tiresfor detecting the temperature of the tires, a processor coupled to thethermal radiation detecting system for receiving the detectedtemperature of the tires and determining whether a difference in thermalradiation is present between associated mated pairs of the tires, and aresponse system coupled to the processor for responding to thedetermined difference in thermal radiation between mated pairs of thetires. Instead of determining whether a difference in thermal radiationis present between associated mated pairs of tires, a comparison oranalysis may be made between the temperature of the tires individuallyand a predetermined value or threshold to determine the status of thetires, e.g., properly inflated, under inflated or delaminated, andappropriate action by the response system is undertaken in light of thecomparison or analysis. The analysis may be in the form of a differencebetween the absolute temperature and the threshold temperature. Evensimpler, an analysis of the detected temperature of each tire may beused and considered in a determination of whether the tire isexperiencing or is about to experience a problem. Such an analysis wouldnot necessarily entail comparison to a threshold.

The determination of which tires constitute mated pairs is made on avehicle-by-vehicle basis and depends on the location of the tires on thevehicle. It is important to determine which tires form mated pairsbecause such tires should ideally have the same pressure and thus thesame temperature. As a result, a difference in temperature between tiresof a mated pair will usually be indicative of a difference in pressurebetween the tires. Such a pressure difference might be the result ofunder-inflation of the tire or a leak. One skilled in the art of tireinflation and maintenance would readily recognize which tires must beinflated to the same pressure and carry substantially the same load sothat such tires would form mated pairs.

For example, for a conventional automobile with four tires, the matedpairs of tires would be the front tires and the rear tires. The fronttires should be inflated to the same tire pressure and carry the sameload so that they would have the same temperature, or have differenttemperatures within an allowed tolerance. Similarly, the rear tiresshould be inflated to the same tire pressure and carry the same load sothat they would have the same temperature, or have differenttemperatures within an allowed tolerance.

It is also conceivable that three or more tires on the vehicle should beat the same temperature and thus form a plurality of mated pairs, i.e.,the designation of one tire as being part of one mated pair does notexclude the tire from being part of another mated pair. Thus, if threetires should be at the same temperature and they each have a differenttemperature, this would usually be indicative of different pressures andthus would give rise to a need to check each tire.

The thermal radiation detecting system is coupled to the processor,preferably in a wireless manner, however wires can also be used alone orin combination with a wireless technique. For example, a suitablecoupling may include a transmitter mounted in connection with thethermal radiation detecting device and a receiver mounted in connectionwith or integrated into the processor. Any of the conventions for wiredor wirelessly transmitting data from a plurality of tirepressure-measuring sensors to a common receiver or multiple receiversassociated with a single processor, as discussed in the U.S. patentsabove, may be used in accordance with the invention.

The thermal radiation detecting system may comprise infrared radiationreceivers each arranged to have a clear field of view of at least onetire. The receivers may be arranged in any location on the vehicle fromwhich a view of at least a part of the tire surface can be obtained. Forexample, the receivers may be arranged in the tire wells around thetires, on the side of the vehicle and on side mounted rear view mirrors.

In order to supply power to the thermal radiation detecting systems ordevices described herein, several innovative approaches are possible inaddition to directly connected wires. Preferably, power is suppliedwirelessly, e.g., inductively, through radio frequency energy transferor capacitively. In the inductive power supply arrangement, the vehicleis provided with a pair of looped wires arranged to pass within a shortdistance from a power receiving system electrically coupled to thethermal radiation detecting devices, i.e., the necessary circuitry andelectronic components to enable an inductive current to develop betweenthe pair of looped wires and a wire of the power receiving system suchas disclosed in U.S. Pat. No. 5,293,308, U.S. Pat. No. 5,450,305, U.S.Pat. No. 5,528,113, U.S. Pat. No. 5,619,078, U.S. Pat. No. 5,767,592,U.S. Pat. No. 5,821,638, U.S. Pat. No. 5,839,554, U.S. Pat. No.5,898,579 and U.S. Pat. No. 6,031,737.

1.4.6 Hall Effect Tire Pressure Monitors

FIGS. 94-97 illustrate improvements to prior art Hall effect tirepressure monitor designs described in U.S. Patent ApplicationPublication No. 2006/0006994 to Moser. Reference is made to Moser fordetails about the operation of such tire pressure monitors.

One of the drawbacks of the Moser tire pressure monitoring designs isthe presence of the coil spring 29 inside the piston 26 to which themagnet 27 is adhered. Several options for replacing the coil spring usedin Moser with different types of springs are proposed and believed toimprove the operation of the tire pressure monitors. Generally, thenovel springs are placed outside of a solid magnet, and not inside of ahollowed piston as in Moser, so that the spring acts directly on themagnet and moves it axially in dependence on the pressure in a channelin a housing which communicates with the interior of the tire, with thehousing being attachable to the wheel rim. Movement of the magnet iscaused by the exertion of forces by the spring on one side and thediaphragm on the other which is exposed to the pressure in the interiorof the housing which communicates with the interior of the tire.

In FIG. 94, the tire pressure sensor assembly is designated generally as829 and includes a Hall effect sensor 824, shown within a magnetic lineof flux 827 generated by magnet 823 which occurs once during eachrotation of the wheel relative to the non-rotating part of the vehicleto which the Hall effect sensor 824 is mounted, and a cantileveredspring 828 mounted at one end to the housing of the sensor assembly andhaving a free opposite end contacting an axial surface of the magnet 823which faces the non-rotating part of the vehicle on which the Halleffect sensor 824 is mounted. In the embodiment shown in FIG. 94A, aspring washer 831 is provided. Spring washer 831 is substantiallycircular and planar and is preferably attached around its periphery tothe housing of the sensor assembly and in contact with an axial surfaceof the magnet 823. These alternate springs have the effect ofsubstantially eliminating the influence of side forces due centripetalaccelerations acting on the magnet 823 as the wheel rotates. Theseaccelerations, which can reach a number of G's in magnitude, addfriction forces and can delay or even prevent the motion of the magnetwhen the vehicle 830 is traveling at high speeds. Thus, a sudden leak ina tire may go unreported.

The Hall effect sensor 824 senses or detects magnetic field density ofthe magnet 823 as the magnet rotates 823, with the sensed or detectedmagnetic field density being convertible into an indication of thepressure in the channel in the housing, which is in communication withthe interior of the tire, and thus an indication of the pressure in thetire. Such a conversion or derivation is known to those skilled in theart, as explained for example, in Moser. The detected magnetic fielddensity may be communicated wirelessly to a processor on the vehicle forfurther processing, as in Moser.

A dust cover 832 is also illustrated in FIG. 94A which can be used inall of the designs discussed herein. Cantilever spring 828 and springwasher 831 are arranged inward of the dust cover 832, i.e., between thedust cover 832 and the surface of the magnet 823 facing the Hall effectsensor 824. A bracket 826, or other comparable structure, attaches theHall effect sensor 824 to the non-rotating part of the vehicle 830 sothat the Hall effect sensor 824 is opposite the wheel rim or othersurface in which or to which the magnet 823 is mounted (and thus will bein the magnetic field generated by the magnet 823 once during rotationof the wheel).

To overcome another drawback of Moser, dual magnets are used in theembodiment shown in FIG. 95, one fixed and one whose position depends onthe pressure in the tire as in the Moser patent application. Thus, asthe tire rotates, each magnet passes the Hall effect sensor 824 almostsimultaneously thereby generating two pulses. This permits a relative ordifferential motion of the moving magnets to be determined therebyeliminating the effect of tolerances due to mounting of the system.

Determining the differential motion of the moving magnets overcomes asignificant drawback of the tire pressure monitors of Moser. A criticalparameter in the tire pressure monitors of Moser is the gap between themagnet and the Hall effect sensor. As this gap changes, the sensitivityof the device also changes and may adversely affect the data provided bythe device. According to Moser, this gap is ideally set at 1-2 mm.Manufacturing tolerances between vehicles for this gap are undoubtedlyon the order of millimeters. As a vehicle ages, this gap will alsochange due to vehicle repairs, damage to the various parts thatcontribute to the gap, and the accumulation of debris especially ironparticles that adhere to the magnet. A stone hitting the bracket thatholds the Hall effect sensor, for example, can deform or dent the sensoror bracket by a millimeter or more.

By changing to a differential motion measurement as in the embodimentshown in FIG. 95 using multiple magnets, this problem is solved. Settingor placement of a fixed magnet 833 can be made such that the gap betweenthe fixed magnet 833 and the Hall effect sensor 824 is the same as thegap between the movable magnet 834 and the Hall effect sensor when thepressure in the tire is proper. As the pressure in the tire drops,magnet 834 moves in a direction to increase the gap, so that as a resultof this movement, a significant difference can be measured in thecurrent or voltage of the Hall effect sensor between the fixed magnet833 and the movable magnet 834. This current or voltage differentialwill exist regardless of the initial gap setting or if that settingchanges due to the effects mentioned above.

More specifically, in a wheel assembly with a tire pressure monitoringsystem using dual magnets 833, 834, the assembly includes a wheel rim, atire mounted thereon, a housing having an interior in flow communicationwith an interior of the tire such that the same pressure prevails in thetire and the interior of the housing, a first, movable magnet (saymagnet 833) arranged in the housing and adapted to be movable in anaxial direction of the wheel rim, and a spring coupled to the housingand arranged to move the first magnet in dependence on pressure in theinterior of the housing. This structure so far may be the structureshown in FIGS. 94 and 94A or that shown in Moser. However, a novelty ofthis embodiment is that the wheel assembly further includes a second,fixed magnet (say magnet 834) fixed to the wheel rim in the same axialposition as the first magnet will be in when the pressure in the tire isproper. This position can be determined by inflating the tire to theproper pressure, determining the position of the movable magnet 833 andthen attaching the fixed magnet 824 to the wheel rim in the same axialposition so that when the tire is at the proper pressure, both magnets833, 834 will be the same distance from the Hall effect sensor 824. TheHall effect sensor senses magnetic field density of the magnets 833, 834as the wheel rim rotates. The magnetic field density of the first magnetis comparable to the magnetic field density of the second magnet withany difference being indicative of the pressure in the tire not beingproper, i.e., the magnets 833, 834 are different distances from the Halleffect sensor 824.

Another concern with the tire pressure monitors of Moser is that noattempt is made to channel the magnetic flux lines so as to make optimumuse of the magnetic field emitted by the magnet. Thus, the size of thegap for a given magnet is limited as most of the flux is lost. A carefulanalysis and design of the magnet circuit is therefore required in orderto make the design robust and optimal. One such design in illustrated inFIG. 96 where magnetic material such as iron is used in parts 835 and836 to channel the magnetic flux from one pole of the wheel-based magnetto the other so that a greater amount of the magnetic field passesthrough the Hall effect sensor 824. A representative flux line isillustrated by the dashed line 827 in FIG. 94 and a modified flux lineas 827A in FIG. 96. In FIG. 96, most of the flux passes through the Halleffect sensor 824 permitting either the magnet to be made weaker, a lessexpensive magnet material to be used, a larger gap to be used, or a lessexpensive Hall effect sensor to be used. Furthermore, once a magneticcircuit is designed and used, the magnet can be placed on the Halleffect sensor assembly rather than on the wheel. By eliminating themagnets on the wheel, the system cost is reduced and the design of thewheel-based system becomes simpler since only a thin piece of iron 838is required (see FIG. 97).

Thus, the embodiments of FIGS. 96 and 97 include structure forchanneling magnetic flux generated by the magnet or magnets as thisstructure can be used with either the single magnet embodiments of FIGS.94 and 94A or those in the prior art such as those in Moser, or thedual-magnet embodiment of FIG. 95. The channeling structure may be a cup835 made of metal such as iron and which defines an interior in whichthe magnet 823 is arranged with the opening of the cup facing the gap,i.e., facing the Hall effect sensor. Alternatively or additionally, thechanneling structure may include a cup 836 defining an interior in whichthe Hall effect sensor 824 is arranged with the opening of this cupfacing the magnet 823.

Additionally and advantageously, the magnet on the Hall effect sensorassembly can be made as an electromagnet 837 which has significantlyless temperature sensitivity and also is less likely to retain ironparticles or other magnetic materials during the life of the vehicle(see FIG. 97). This feature can also be used with the embodimentsdescribed in FIGS. 93-96.

It is important to note that in the embodiment shown in FIG. 97, thehousing defining the channel communicating with the interior of the tireincludes only a diaphragm and a piece of metallic material, such as apiece of iron 838 which may be securely attached to the diaphragm sothat as the pressure in the tire changes, the diaphragm moves and thusthe piece of iron 838 moves. A magnet is not placed on the rotating tirebut rather is placed on the non-rotating part of the vehicle, i.e., onthe Hall effect sensor assembly.

1.6 Occupant Sensing

Occupant or object presence and position sensing is another field inwhich SAW and/or RFID technology can be applied and the inventionsherein encompasses several embodiments of SAW and RFID occupant orobject presence and/or position sensors.

Many sensing systems are available to identify and locate occupants orother objects in a passenger compartment of the vehicle. Such sensorsinclude ultrasonic sensors, chemical sensors (e.g., carbon dioxide),cameras and other optical sensors, radar systems, heat and otherinfrared sensors, capacitance, magnetic or other field change sensors,etc. Most of these sensors require power to operate and returninformation to a central processor for analysis. An ultrasonic sensor,for example, may be mounted in or near the headliner of the vehicle andperiodically it transmits a burst of ultrasonic waves and receivesreflections of these waves from occupying items of the passenger seat.Current systems on the market are controlled by electronics in adedicated ECU.

FIG. 68 is a side view, with parts cutaway and removed of a vehicleshowing the passenger compartment containing a rear-facing child seat342 on a front passenger seat 343 and one mounting location for a firstembodiment of a vehicle interior monitoring system in accordance withthe invention. The interior monitoring system is capable of detectingthe presence of an object, determining the type of object, determiningthe location of the object, and/or determining another property orcharacteristic of the object. A property of the object could be thepresence or orientation of a child seat, the velocity of an adult andthe like. For example, the vehicle interior monitoring system candetermine that an object is present on the seat, that the object is achild seat and that the child seat is rear-facing. The vehicle interiormonitoring system could also determine that the object is an adult, thathe is drunk and that he is out-of-position relative to the airbag.

In this embodiment, six transducers 344, 345, 346, 347, 348 and 349 areused, although any number of transducers may be used. Each transducer344, 345, 346, 347, 348, 349 may comprise only a transmitter whichtransmits energy, waves or radiation, only a receiver which receivesenergy, waves or radiation, both a transmitter and a receiver capable oftransmitting and receiving energy, waves or radiation, an electric fieldsensor, a capacitive sensor, or a self-tuning antenna-based sensor,weight sensor, chemical sensor, motion sensor or vibration sensor, forexample.

Such transducers or receivers 344-349 may be of the type which emit orreceive a continuous signal, a time varying signal (such as a capacitoror electric field sensor) or a spatial varying signal such as in ascanning system. One particular type of radiation-receiving receiver foruse in the invention is a receiver capable of receiving electromagneticwaves.

When ultrasonic energy is used, transducer 345 can be used as atransmitter and transducers 344,346 as receivers. Naturally, othercombinations can be used such as where all transducers are transceivers(transmitters and receivers). For example, transducer 345 can beconstructed to transmit ultrasonic energy toward the front passengerseat, which is modified, in this case by the occupying item of thepassenger seat, i.e., the rear-facing child seat 342, and the modifiedwaves are received by the transducers 344 and 346, for example. A morecommon arrangement is where transducers 344, 345 and 346 are alltransceivers. Modification of the ultrasonic energy may constitutereflection of the ultrasonic energy as the ultrasonic energy isreflected back by the occupying item of the seat. The waves received bytransducers 344 and 346 vary with time depending on the shape of theobject occupying the passenger seat, in this case, the rear-facing childseat 342. Each object will reflect back waves having a differentpattern. Also, the pattern of waves received by transducer 344 willdiffer from the pattern received by transducer 346 in view of itsdifferent mounting location. This difference generally permits thedetermination of the location of the reflecting surface (i.e., therear-facing child seat 342) through triangulation. Through the use oftwo transducers 344,346, a sort of stereographic image is received bythe two transducers and recorded for analysis by processor 340, which iscoupled to the transducers 344,345,346. This image will differ for eachobject that is placed on the vehicle seat and it will also change foreach position of a particular object and for each position of thevehicle seat. Elements 344,345,346, although described as transducers,are representative of any type of component used in a wave-basedanalysis technique.

For ultrasonic systems, the “image” recorded from each ultrasonictransducer/receiver, is actually a time series of digitized data of theamplitude of the received signal versus time. Since there are tworeceivers, two time series are obtained which are processed by theprocessor 340. The processor 340 may include electronic circuitry andassociated, embedded software. Processor 340 constitutes one form of agenerating system in accordance with the invention which generatesinformation about the occupancy of the passenger compartment based onthe waves received by the transducers 344,345,346.

When different objects are placed on the front passenger seat, the twoimages from transducers 344,346, for example, are different but thereare also similarities between all images of rear-facing child seats, forexample, regardless of where on the vehicle seat they are placed andregardless of what company manufactured the child seat. Alternately,there will be similarities between all images of people sitting on theseat regardless of what they are wearing, their age or size. The problemis to find the “rules” which differentiate the images of one type ofobject from the images of other types of objects, e.g., whichdifferentiate the occupant images from the rear-facing child seatimages. The similarities of these images for various child seats arefrequently not obvious to a person looking at plots of the time seriesand thus computer algorithms are developed to sort out the variouspatterns. For a more detailed discussion of pattern recognition, seeU.S. Pat. No. 5,943,295 to Varga et al.

The determination of these rules is important to the pattern recognitiontechniques used in this invention. In general, three approaches havebeen useful, artificial intelligence, fuzzy logic and artificial neuralnetworks (including cellular and modular or combination neural networksand support vector machines) (although additional types of patternrecognition techniques may also be used, such as sensor fusion). In someembodiments of this invention, such as the determination that there isan object in the path of a closing window as described below, the rulesare sufficiently obvious that a trained researcher can sometimes look atthe returned signals and devise an algorithm to make the requireddeterminations. In others, such as the determination of the presence ofa rear-facing child seat or of an occupant, artificial neural networksare used to determine the rules. One such set of neural network softwarefor determining the pattern recognition rules is available from theInternational Scientific Research, Inc. of Panama City, Panama and Kyiv,Ukraine.

The system used in a preferred implementation of inventions herein forthe determination of the presence of a rear-facing child seat, of anoccupant or of an empty seat is the artificial neural network. In thiscase, the network operates on the two returned signals as sensed bytransducers 344 and 346, for example. Through a training session, thesystem is taught to differentiate between the three cases. This is doneby conducting a large number of experiments where all possible childseats are placed in all possible orientations on the front passengerseat. Similarly, a sufficiently large number of experiments are run withhuman occupants and with boxes, bags of groceries and other objects(both inanimate and animate). Sometimes, as many as 1,000,000 suchexperiments are run before the neural network is sufficiently trained sothat it can differentiate among the three cases and output the correctdecision with a very high probability. Of course, it must be realizedthat a neural network can also be trained to differentiate amongadditional cases, e.g., a forward-facing child seat.

Once the network is determined, it is possible to examine the resultusing tools supplied International Scientific Research, for example, todetermine the rules that were finally arrived at by the trial and errortechniques. In that case, the rules can then be programmed into amicroprocessor resulting in a fuzzy logic or other rule-based system.Alternately, a neural computer, or cellular neural network, can be usedto implement the net directly. In either case, the implementation can becarried out by those skilled in the art of pattern recognition. If amicroprocessor is used, a memory device is also required to store thedata from the analog-to-digital converters that digitize the data fromthe receiving transducers. On the other hand, if a neural networkcomputer is used, the analog signal can be fed directly from thetransducers to the neural network input nodes and an intermediate memoryis not required. Memory of some type is needed to store the computerprograms in the case of the microprocessor system and if the neuralcomputer is used for more than one task, a memory is needed to store thenetwork specific values associated with each task.

Electromagnetic energy-based occupant sensors exist that use variousportions of the electromagnetic spectrum. A system based on theultraviolet, visible or infrared portions of the spectrum generallyoperate with a transmitter and a receiver of reflected radiation. Thereceiver may be a camera, focal plane array, or a photo detector such asa pin or avalanche diode as described in detail in above-referencedpatents and patent applications. At other frequencies, the absorption ofthe electromagnetic energy is primarily and at still other frequencies,the capacitance or electric field influencing effects are used.Generally, the human body will reflect, scatter, absorb or transmitelectromagnetic energy in various degrees depending on the frequency ofthe electromagnetic waves. All such occupant sensors are includedherein.

In the embodiment wherein electromagnetic energy is used, it is to beappreciated that any portion of the electromagnetic signals thatimpinges upon, surrounds or involves a body portion of the occupant isat least partially absorbed by the body portion. Sometimes, this is dueto the fact that the human body is composed primarily of water, and thatelectromagnetic energy of certain frequencies is readily absorbed bywater. The amount of electromagnetic signal absorption is related to thefrequency of the signal, and size or bulk of the body portion that thesignal impinges upon. For example, a torso of a human body tends toabsorb a greater percentage of electromagnetic energy than a hand of ahuman body.

Thus, when electromagnetic waves or energy signals are transmitted by atransmitter, the returning waves received by a receiver provide anindication of the absorption of the electromagnetic energy. That is,absorption of electromagnetic energy will vary depending on the presenceor absence of a human occupant, the occupant's size, bulk, surfacereflectivity, etc. depending on the frequency, so that different signalswill be received relating to the degree or extent of absorption by theoccupying item on the seat. The receiver will produce a signalrepresentative of the returned waves or energy signals which will thusconstitute an absorption signal as it corresponds to the absorption ofelectromagnetic energy by the occupying item in the seat.

One or more of the transducers 344,345,346 can also be image-receivingdevices, such as cameras, which take images of the interior of thepassenger compartment. These images can be transmitted to a remotefacility to monitor the passenger compartment or can be stored in amemory device for use in the event of an accident, i.e., to determinethe status of the occupants of the vehicle prior to the accident. Inthis manner, it can be ascertained whether the driver was fallingasleep, talking on the phone, etc.

To aid in the detection of the presence of child seats as well as theirorientation, a device 341 can be placed on the child seat in someconvenient location where its presence can be sensed by avehicle-mounted sensor that can be in the seat, dashboard, headliner orany other convenient location depending on the system design. The device341 can be a reflector, resonator, RFID tag, SAW device, or any othertag or similar device that permits easy detection of its presence andperhaps its location or proximity. Such a device can also be placed onany other component in the vehicle to indicate the presence, location oridentity of the component. For example, a vehicle may have a changeablecomponent where the properties of that component are used by anothersystem within the vehicle and thus the identification of the particularobject is needed so that the proper properties are used by the othersystem. An occupant monitoring system (e.g. ultrasonic, optical,electric field, etc.) may perform differently depending on whether theseat is made from cloth or leather or a weight sensor may depend on theproperties of a particular seat to provide the proper occupant weight.Thus, incorporation of an RFID, SAW, barcode or other tag or mark on anyobject that can be interrogated by an interrogator is contemplatedherein.

A memory device for storing the images of the passenger compartment, andalso for receiving and storing any of the other information, parametersand variables relating to the vehicle or occupancy of the vehicle, maybe in the form a standardized “black box” (instead of or in addition toa memory part in a processor 340). The IEEE Standards Association iscurrently beginning to develop an international standard for motorvehicle event data recorders. The information stored in the black boxand/or memory unit in the processor 340, can include the images of, orother information related to, the interior of the passenger compartmentas well as the number of occupants and the health state of theoccupants. The black box would preferably be tamper-proof andcrash-proof and enable retrieval of the information after a crash. Theuse of wave-type sensors as the transducers 344,345,346 as well aselectric field sensors is discussed above. Electric field sensors andwave sensors are essentially the same from the point of view of sensingthe presence of an occupant in a vehicle. In both cases, a time-varyingelectric field is disturbed or modified by the presence of the occupant.At high frequencies in the visual, infrared and high frequency radiowave region, the sensor is based on its capability to sense change ofwave characteristics of the electromagnetic field, such as amplitude,phase or frequency. As the frequency drops, other characteristics of thefield are measured. At still lower frequencies, the occupant'sdielectric properties modify parameters of the reactive electric fieldin the occupied space between/near the plates of a capacitor. In thislatter case, the sensor senses the change in charge distribution on thecapacitor plates by measuring, for example, the current wave magnitudeor phase in the electric circuit that drives the capacitor. Thesemeasured parameters are directly connected with parameters of thedisplacement current in the occupied space. In all cases, the presenceof the occupant reflects, absorbs or modifies the waves or variations inthe electric field in the space occupied by the occupant. Thus, for thepurposes of this invention, capacitance, electric field orelectromagnetic wave sensors are equivalent and although they are alltechnically “field” sensors they can be considered as “wave” sensorsherein. What follows is a discussion comparing the similarities anddifferences between two types of field or wave sensors, electromagneticwave sensors and capacitive sensors as exemplified by Kithil in U.S.Pat. No. 5,602,734 (see also U.S. Pat. No. 6,275,146, U.S. Pat. No.6,014,602, U.S. Pat. No. 5,844,486, U.S. Pat. No. 5,802,479, U.S. Pat.No. 5,691,693 and U.S. Pat. No. 5,366,241).

An electromagnetic field disturbed or emitted by a passenger in the caseof an electromagnetic wave sensor, for example, and the electric fieldsensor of Kithil, for example, are in many ways similar and equivalentfor the purposes of this invention. The electromagnetic wave sensor isan actual electromagnetic wave sensor by definition because it sensesparameters of a wave, which is a coupled pair of continuously changingelectric and magnetic fields. The electric field here is not a static,potential one. It is essentially a dynamic, rotational electric fieldcoupled with a changing magnetic one, that is, an electromagnetic wave.It cannot be produced by a steady distribution of electric charges. Itis initially produced by moving electric charges in a transmitter, evenif this transmitter is a passenger body for the case of a passiveinfrared sensor.

In the Kithil sensor, a static electric field is declared as an initialmaterial agent coupling a passenger and a sensor (see Column 5, lines5-7): “The proximity sensor 12 each function by creating anelectrostatic field between oscillator input loop 54 and detector outputloop 56, which is affected by presence of a person near by, as a resultof capacitive coupling, . . . ”. It is a potential, non-rotationalelectric field. It is not necessarily coupled with any magnetic field.It is the electric field of a capacitor. It can be produced with asteady distribution of electric charges. Thus, it is not anelectromagnetic wave by definition but if the sensor is driven by avarying current, then it produces a quasistatic electric field in thespace between/near the plates of the capacitor.

Kithil declares that his capacitance sensor uses a static electricfield. Thus, from the consideration above, one can conclude thatKithil's sensor cannot be treated as a wave sensor because there are noactual electromagnetic waves but only a static electric field of thecapacitor in the sensor system. However, this is not believed to be thecase. The Kithil system could not operate with a true static electricfield because a steady system does not carry any information. Therefore,Kithil is forced to use an oscillator, causing an alternate current inthe capacitor and a reactive quasi-static electric field in the spacebetween the capacitor plates, and a detector to reveal an informativechange of the sensor capacitance caused by the presence of an occupant(see FIG. 7 and its description in the '734 patent). In this case, thesystem becomes a “wave sensor” in the sense that it starts generatingactual time-varying electric field that certainly originateselectromagnetic waves according to the definition above. That is,Kithil's sensor can be treated as a wave sensor regardless of the shapeof the electric field that it creates a beam or a spread shape.

As follows from the Kithil patent, the capacitor sensor is likely aparametric system where the capacitance of the sensor is controlled bythe influence of the passenger body. This influence is transferred bymeans of the near electromagnetic field (i.e., the wave-like process)coupling the capacitor electrodes and the body. It is important to notethat the same influence takes place with a real static electric fieldalso, that is in absence of any wave phenomenon. This would be asituation if there were no oscillator in Kithil's system. However, sucha system is not workable and thus Kithil reverts to a dynamic systemusing time-varying electric fields.

Thus, although Kithil declares the coupling is due to a static electricfield, such a situation is not realized in his system because analternating electromagnetic field (“quasi-wave”) exists in the systemdue to the oscillator. Thus, the sensor is actually a wave sensor, thatis, it is sensitive to a change of a wave field in the vehiclecompartment. This change is measured by measuring the change of itscapacitance. The capacitance of the sensor system is determined by theconfiguration of its electrodes, one of which is a human body, that is,the passenger inside of and the part which controls the electrodeconfiguration and hence a sensor parameter, the capacitance.

The physics definition of “wave” from Webster's Encyclopedic UnabridgedDictionary is: “11. Physics. A progressive disturbance propagated frompoint to point in a medium or space without progress or advance of thepoints themselves, . . . ”. In a capacitor, the time that it takes forthe disturbance (a change in voltage) to propagate through space, thedielectric and to the opposite plate is generally small and neglectedbut it is not zero. As the frequency driving the capacitor increases andthe distance separating the plates increases, this transmission time asa percentage of the period of oscillation can become significant.Nevertheless, an observer between the plates will see the rise and fallof the electric field much like a person standing in the water of anocean in the presence of water waves. The presence of a dielectric bodybetween the plates causes the waves to get bigger as more electrons flowto and from the plates of the capacitor. Thus, an occupant affects themagnitude of these waves which is sensed by the capacitor circuit. Theelectromagnetic field is a material agent that carries information abouta passenger's position in both Kithil's and a beam-type electromagneticwave sensor.

Considering now a general occupant sensor and its connection to the restof the system, an alternate method as taught herein is to use aninterrogator to send a signal to the headliner-mounted ultrasonicsensor, for example, causing that sensor to transmit and receiveultrasonic waves. The sensor in this case could perform mathematicaloperations on the received waves and create a vector of data containingperhaps twenty to forty values and transmit that vector wirelessly tothe interrogator. By means of this system, the ultrasonic sensor needonly be connected to the vehicle power system and the information can betransferred to and from the sensor wirelessly (either by electromagneticor ultrasonic waves or equivalent). Such a system significantly reducesthe wiring complexity especially when there may be multiple such sensorsdistributed in the passenger compartment. Then, only a power wire needsto be attached to the sensor and there does not need to be any directconnection between the sensor and the control module. The samephilosophy applies to radar-based sensors, electromagnetic sensors ofall kinds including cameras, capacitive or other electromagnetic fieldchange sensitive sensors etc. In some cases, the sensor itself canoperate on power supplied by the interrogator through radio frequencytransmission. In this case, even the connection to the power line can beomitted. This principle can be extended to the large number of sensorsand actuators that are currently in the vehicle where the only wiresthat are needed are those to supply power to the sensors and actuatorsand the information is supplied wirelessly.

Such wireless powerless sensors can also be used, for example, as closeproximity sensors based on measurement of thermal radiation from anoccupant. Such sensors can be mounted on any of the surfaces in thepassenger compartment, including the seats, which are likely to receivesuch radiation.

A significant number of people are suffocated each year in automobilesdue to excessive heat, carbon dioxide, carbon monoxide, or otherdangerous fumes. The SAW sensor technology is particularly applicable tosolving these kinds of problems. The temperature measurementcapabilities of SAW transducers have been discussed above. If thesurface of a SAW device is covered with a material which captures carbondioxide, for example, such that the mass, elastic constants or otherproperty of surface coating changes, the characteristics of the surfaceacoustic waves can be modified as described in detail in U.S. Pat. No.4,637,987 and elsewhere based on the carbon dioxide content of the air.Once again, an interrogator can sense the condition of thesechemical-sensing sensors without the need to supply power. Theinterrogator can therefore communicate with the sensors wirelessly. Ifpower is supplied then this communication can be through the wires. If aconcentration of carbon monoxide is sensed, for example, an alarm can besounded, the windows opened, and/or the engine extinguished. Similarly,if the temperature within the passenger compartment exceeds a certainlevel, the windows can be automatically opened a little to permit anexchange of air reducing the inside temperature and thereby perhapssaving the life of an infant or pet left in the vehicle unattended.

In a similar manner, the coating of the surface wave device can containa chemical which is responsive to the presence of alcohol. In this case,the vehicle can be prevented from operating when the concentration ofalcohol vapors in the vehicle exceeds some predetermined limit. Such adevice can advantageously be mounted in the headliner above the driver'sseat.

Each year, a number of children and animals are killed when they arelocked into a vehicle trunk. Since children and animals emit significantamounts of carbon dioxide, a carbon dioxide sensor connected to thevehicle system wirelessly and powerlessly provides an economic way ofdetecting the presence of a life form in the trunk. If a life form isdetected, then a control system can release a trunk lock thereby openingthe trunk. Alarms can also be sounded or activated when a life form isdetected in the trunk. An infrared or other sensor can perform a similarfunction.

FIG. 69 illustrates a SAW strain gage as described above, where thetension in the seat belt 350 can be measured without the requirement ofpower or signal wires. FIG. 69 illustrates a powerless and wirelesspassive SAW strain gage-based device 357 for this purpose. There aremany other places that such a device can be mounted to measure thetension in the seatbelt at one place or at multiple places.Additionally, a SAW-based accelerometer can be located on the seatbeltadjacent the chest of an occupant as a preferred measure of the stressplaced on the occupant by the seatbelt permitting that stress to becontrolled.

In FIG. 73, a bolt 360 is used to attach a vehicle seat to a supportstructure such as a slide mechanism as illustrated in FIGS. 21 and 22,among others, in U.S. Pat. No. 6,242,701. The bolt 360 is attached tothe seat or seat structure (not shown) by inserting threaded section 361containing threads 362 and then attaching a nut (not shown) to securethe bolt 360 to the seat or seat structure. Similarly, the lower sectionof the bolt 360 is secured to the slide mechanism (not shown) by lowerbolt portion 363 by means of a nut (not shown) engaging threads 364.Four such bolts 360 are typically used to attach the seat to thevehicle.

As the weight in the seat increases, the load is transferred to thevehicle floor by means of stresses in bolts 360. The stress in the boltsection 365 is not affect by stresses in the bolt sections 361 and 363caused by the engagement of the nuts that attach the bolts 360 to theseat and vehicle respectively.

The silicon strain gage 366 is attached, structured and arranged tomeasure the strain in bolt section 365 caused by loading from the seatand its contents. Silicon strain gage 366 is selected for its high gagefactor and low power requirements relative to other strain gagetechnologies. Associated electronics 367 are typically incorporated intoa single chip and may contain connections/couplings for wires, notshown, or radio frequency circuits and an antenna for radio frequencytransfer of power and signals from the strain gage 366 to aninterrogator mounted on the vehicle, not shown. In this manner, theinterrogator supplies power and receives the instantaneous strain valuethat is measured by the strain gage 366.

Although a single strain element 366 has been illustrated, the bolt 360may contain 1, 2, or even as many as 4 such strain gage assemblies onvarious sides of bolt section 365. Other stain gage technologies canalso be used.

Another example of a stud which is threaded on both ends and which canbe used to measure the weight of an occupant seat is illustrated inFIGS. 74A-74D. The operation of this device is disclosed in U.S. Pat.No. 6,653,577 wherein the center section of stud 371 is solid. It hasbeen discovered that sensitivity of the device can be significantlyimproved if a slotted member is used as described in U.S. Pat. No.5,539,236. FIG. 74A illustrates a SAW strain gage 372 mounted on asubstrate and attached to span a slot 374 in a center section 375 of thestud 371. This technique can be used with any other strain-measuringdevice.

FIG. 74B is a side view of the device of FIG. 74A.

FIG. 74C illustrates use of a single hole 376 drilled off-center in thecenter section 375 of the stud 371. The single hole 376 also serves tomagnify the strain as sensed by the strain gage 372. It has theadvantage in that strain gage 372 does not need to span an open space.The amount of magnification obtained from this design, however, issignificantly less than obtained with the design of FIG. 74A.

To improve the sensitivity of the device shown in FIG. 74C, multiplesmaller holes 377 can be used as illustrated in FIG. 74D. FIG. 74E in analternate configuration showing three of four gages 372 for determiningthe bending moments as well as the axial stress in the support member.

In operation, the SAW strain gage 372 receives radio frequency wavesfrom an interrogator 378 and returns electromagnetic waves via arespective antenna 373 which are delayed based on the strain sensed bystrain gage 372.

Occupant weight sensors can give erroneous results if the seatbelt ispulled tight pushing the occupant into the seat. This is particularly aproblem when the seatbelt is not attached to the seat. For such cases,it has been proposed to measure the tension in various parts of theseatbelt. Conventional technology requires that such devices behard-wired into the vehicle complicating the wire harness.

Other components of the vehicle can also be wirelessly coupled to theprocessor or central control module for the purposes of datatransmission and/or power transmission. A discussion of some componentsfollows.

Seat Systems

In more enhanced applications, it is envisioned that components of theseat will be integrated into the power transmission and communicationsystem. In many luxury cars, the seat subsystem is becoming verycomplicated. Seat manufacturers state that almost all warranty repairsare associated with the wiring and connectors associated with the seat.The reliability of seat systems can therefore be substantially improvedand the incidence of failures or warranty repairs drastically reduced ifthe wires and connectors can be eliminated from the seat subsystem.

Today, there are switches located on the seat or at other locations inthe vehicle for controlling the forward and backward motions, up anddown motions, and rotation of the seat and seat back. These switches areconnected to the appropriate motors by wires. Additionally, many seatsnow contain an airbag that must communicate with a sensor located, forexample, in the vehicle, B-pillar, sill or door. Many occupant presencesensors and weight sensing systems are also appearing on vehicle seats.Finally, some seats contain heaters and cooling elements, vibrators, andother comfort and convenience devices that require wires and switches.

As an example, let us now look at weight sensing. Under the teachings ofan invention disclosed herein, silicon strain gage weight sensors can beplaced on the bolts that secure each seat to the slide mechanism asshown in FIG. 73. These strain gage subsystems can contain sufficientelectronics and inductive pickup coils so as to receive theiroperational energy from a pair of wires appropriately placed beneath theseats. The seat weight measurements can then be superimposed on thepower frequency or transmitted wirelessly using RF or other convenientwireless technology. Other weight sensing technologies such as bladdersand pressure sensors or two-dimensional resistive deflection sensingmats can also be handled in a similar manner.

Other methods of seat weight sensing include measuring the deflection ofa part of the seat or the deflection of the bolts that connect the seatto the seat slide. For example, the strain in a bolt can be readilydetermined using, for example, SAW, wire or silicon strain gages,optical fiber strain gages, time of flight or phase of ultrasonic wavestraveling through the strained bolt, or the capacitive change of twoappropriately position capacitor plates.

Using the loosely coupled inductive system described above, power inexcess of a kilowatt can be readily transferred to operate seat positionmotors without the use of directly connected wires. The switches canalso be coupled into the inductive system without any direct wireconnections and the switches, which now can be placed on the doorarmrest or on the seat as desired, can provide the information tocontrol the seat motors. Additionally, since microprocessors will now bepresent on every motor and switch, the classical problem of the four-wayseat system to control three degrees of freedom can be easily solved.

In current four-way seat systems, when an attempt is made to verticallyraise the seat, the seat also rotates. Similarly, when an attempt ismade to rotate the seat, it also invariably moves either up or down.This is because there are four switches to control three degrees offreedom and thus there is an infinite combination of switch settings foreach seat position setting. This problem can be easily solved with analgorithm that translates the switch settings to the proper motorpositions. Thus only three switches are needed.

The positions of the seat, seatback and headrest, can also be readilymonitored without having direct wire connections to the vehicle. Thiscan be done in numerous ways beginning with the encoder system that iscurrently in use and ending with simple RFID radar reflective tags thatcan be interrogated by a remote RFID tag reader. Based on the time offlight of RF waves, the positions of all of the desired surfaces of theseat can be instantly determined wirelessly.

1.7 Vehicle or Component Control

At least one invention herein is also particularly useful in light ofthe foreseeable implementation of smart highways. Smart highways willresult in vehicles traveling down highways under partial or completecontrol of an automatic system, i.e., not being controlled by thedriver. The on-board diagnostic system will thus be able to determinefailure of a component prior to or upon failure thereof and inform thevehicle's guidance system to cause the vehicle to move out of the streamof traffic, i.e., onto a shoulder of the highway, in a safe and orderlymanner. Moreover, the diagnostic system may be controlled or programmedto prevent the movement of the disabled vehicle back into the stream oftraffic until the repair of the component is satisfactorily completed.

In a method in accordance with this embodiment, the operation of thecomponent would be monitored and if abnormal operation of the componentis detected, e.g., by any of the methods and apparatus disclosed herein(although other component failure systems may of course be used in thisimplementation), the guidance system of the vehicle which controls themovement of the vehicle would be notified, e.g., via a signal from thediagnostic module to the guidance system, and the guidance system wouldbe programmed to move the vehicle out of the stream of traffic, or offof the restricted roadway, possibly to a service station or dealer, uponreception of the particular signal from the diagnostic module.

The automatic guidance systems for vehicles traveling on highways may beany existing system or system being developed, such as one based onsatellite positioning techniques or ground-based positioning techniques.It can also be based on vision systems such as those used to providelane departure warning. Since the guidance system may be programmed toascertain the vehicle's position on the highway, it can determine thevehicle's current position, the nearest location out of the stream oftraffic, or off of the restricted roadway, such as an appropriateshoulder or exit to which the vehicle may be moved, and the path ofmovement of the vehicle from the current position to the location out ofthe stream of traffic, or off of the restricted roadway. The vehicle maythus be moved along this path under the control of the automaticguidance system. In the alternative, the path may be displayed to adriver (on a heads-up or other display for example) and the driver canfollow the path, i.e., manually control the vehicle. The diagnosticmodule and/or guidance system may be designed to prevent re-entry of thevehicle into the stream of traffic, or off of the restricted roadway,until the abnormal operation of the component is satisfactorilyaddressed.

FIG. 75 is a flow chart of some of the methods for directing a vehicleoff of a roadway if a component is operating abnormally. The component'soperation is monitored at step 380 and a determination is made at step381 whether its operation is abnormal. If not, the operation of thecomponent is monitored further. If the operation of the component isabnormal, the vehicle can be directed off the roadway at step 382. Moreparticularly, this can be accomplished by generating a signal indicatingthe abnormal operation of the component at step 383, directing thissignal to a guidance system in the vehicle at step 384 that guidesmovement of the vehicle off of the roadway at step 385. Also, if thecomponent is operating abnormally, the current position of the vehicleand the location of a site off of the roadway can be determined at step386, e.g., using satellite-based or ground-based location determiningtechniques, a path from the current location to the off-roadway locationdetermined at step 387 and then the vehicle directed along this path atstep 388. Periodically, a determination is made at step 389 whether thecomponent's abnormality has been satisfactorily addressed and/orcorrected and if so, the vehicle can re-enter the roadway and operationof the component begins again. If not, the re-entry of the vehicle ontothe roadway is prevented at step 390.

FIG. 76 schematically shows the basic components for performing thismethod, i.e., a component operation monitoring system 391 (such asdescribed above), an optional satellite-based or ground-basedpositioning system 392 and a vehicle guidance system 393.

2.0 Telematics

2.1 Transmission of Vehicle and Occupant Information

Described herein is a system for determining the status of occupants ina vehicle, and/or of the vehicle, and in the event of an accident or atany other appropriate time, transmitting the status of the occupantsand/or the vehicle, and optionally additional information, via acommunications channel or link to a remote monitoring facility. Inaddition to the status of the occupant, it is also important to be ableto analyze the operating conditions of the vehicle and detect when acomponent of the vehicle is about to fail. By notifying the driver, adealer or other repair facility and/or the vehicle manufacturer of theimpending failure of the component, appropriate corrective action can betaken to avoid such failure.

As noted above, at least one invention herein relates generally totelematics and the transmission of information from a vehicle to one ormore remote sites which can react to the position or status of thevehicle or occupant(s) therein.

Initially, sensing of the occupancy of the vehicle and the optionaltransmission of this information, which may include images, to remotelocations will be discussed. This entails obtaining information fromvarious sensors about the occupant(s) in the passenger compartment ofthe vehicle, e.g., the number of occupants, their type and their motion,if any. Thereafter, general vehicle diagnostic methods will be discussedwith the diagnosis being transmittable via a communications device tothe remote locations. Finally, a discussion of various sensors for useon the vehicle to sense different operating parameters and conditions ofthe vehicle is provided. All of the sensors discussed herein can becoupled to a communications device enabling transmission of data,signals and/or images to the remote locations, and reception of the samefrom the remote locations.

FIG. 77 shows schematically the interface between a vehicle interiormonitoring system in accordance with the invention and the vehicle'scellular or other telematics communication system. An adult occupant 395is shown sitting on the front passenger seat 343 and four transducers344, 345, 347 and 348 are used to determine the presence (or absence) ofthe occupant on that seat 343. One of the transducers 345 in this caseacts as both a transmitter and receiver while transducer 344 can actonly as a receiver or as both a transmitter and receiver. Alternately,transducer 344 could serve as both a transmitter and receiver or thetransmitting function could be alternated between the two transducers344, 345. Also, in many cases more than two transmitters and receiversare used and in still other cases, other types of sensors, such aselectric field, capacitance, self-tuning antennas (collectivelyrepresented by 347 and 348), weight, seatbelt, heartbeat, motion andseat position sensors, are also used in combination with the radiationsensors.

For a general object, transducers 344, 345, 347, 348 can also be used todetermine the type of object, determine the location of the objectand/or determine another property or characteristic of the object. Aproperty of the object could be the presence and/or orientation of achild seat, the velocity of an adult and the like. For example, thetransducers 344, 345, 347, 348 can be designed to enable a determinationthat an object is present on the seat, that the object is a child seatand that the child seat is rear-facing.

The transducers 344 and 345 are attached to the vehicle buried in theA-pillar trim, where their presence can be disguised, and are connectedto processor 340 that may also be hidden in the trim as shown (thisbeing a non-limiting position for the processor 340). Other mountinglocations can also be used. For example, transducers 344, 345 can bemounted inside the seat (along with or in place of transducers 347 and348), in the ceiling of the vehicle, in the B-pillar, in the C-pillarand in the doors. Indeed, the vehicle interior monitoring system inaccordance with the invention may comprise a plurality of monitoringunits, each arranged to monitor a particular seating location. In thiscase, for the rear seating locations, transducers might be mounted inthe B-pillar or C-pillar or in the rear of the front seat or in the rearside doors. Possible mounting locations for transducers, transmitters,receivers and other occupant sensing devices are disclosed in theabove-referenced patents and patent applications and all of thesemounting locations are contemplated for use with the transducersdescribed herein.

The cellular phone or other communications system 396 outputs to anantenna 397. The transducers 344, 345, 347 and 348 in conjunction withthe pattern recognition hardware and software, which is implemented inprocessor 340 and is packaged on a printed circuit board or flex circuitalong with the transducers 344 and 345, determine the presence of anoccupant within a few seconds after the vehicle is started, or within afew seconds after the door is closed. Similar systems located to monitorthe remaining seats in the vehicle also determine the presence ofoccupants at the other seating locations and this result is stored inthe computer memory which is part of each monitoring system processor340.

Periodically and in particular in the event of or in anticipation of anaccident, the electronic system associated with the cellular phone orother telematics system 396 interrogates the various interior monitoringsystem memories and arrives at a count of the number of occupants in thevehicle, and optionally, even makes a determination as to whether eachoccupant was wearing a seatbelt and if he or she is moving after theaccident. The phone or other communications system then automaticallydials or otherwise contacts the EMS operator (such as 911 or through atelematics service such as OnStar®) and the information obtained fromthe interior monitoring systems is forwarded so that a determination canbe made as to the number of ambulances and other equipment to send tothe accident site, for example. Such vehicles will also have a system,such as the global positioning system, which permits the vehicle todetermine its exact location and to forward this information to the EMSoperator, for example.

An alternate preferred communications system is the use of satelliteinternet or Wi-Fi internet such is expected to be operational onvehicles in a few years. In this manner, the vehicle will always havecommunications access regardless of its location on the earth. This isbased on the premise that Wi-Fi will be in place for all those locationswhere satellite communication is not available such as in tunnels, urbancanyons and the like.

Thus, in basic embodiments of the invention, wave or otherenergy-receiving transducers are arranged in the vehicle at appropriatelocations, trained if necessary depending on the particular embodiment,and function to determine whether a life form is present in the vehicleand if so, how many life forms are present and where they are locatedetc. To this end, transducers can be arranged to be operative at only asingle seating locations or at multiple seating locations with aprovision being made to eliminate repetitive count of occupants. Adetermination can also be made using the transducers as to whether thelife forms are humans, or more specifically, adults, children in childseats, etc. As noted above, this is possible using pattern recognitiontechniques. Moreover, the processor or processors associated with thetransducers can be trained to determine the location of the life forms,either periodically or continuously or possibly only immediately before,during and after a crash. The location of the life forms can be asgeneral or as specific as necessary depending on the systemrequirements, i.e., that a human is situated on the driver's seat in anormal position (general) or a determination can be made that a human issituated on the driver's seat and is leaning forward and/or to the sideat a specific angle as well as the position of his or her extremitiesand head and chest (specifically). The degree of detail is limited byseveral factors, including, for example, the number, type and positionof transducers and training of the pattern recognition algorithm.

In addition to the use of transducers to determine the presence andlocation of occupants in a vehicle, other sensors could also be used.For example, a heartbeat sensor which determines the number and presenceof heartbeats can also be arranged in the vehicle, which would thus alsodetermine the number of occupants as the number of occupants would beequal to the number of heartbeats. Conventional heartbeat sensors can beadapted to differentiate between a heartbeat of an adult, a heartbeat ofa child and a heartbeat of an animal. As its name implies, a heartbeatsensor detects a heartbeat, and the magnitude thereof, of a humanoccupant of the seat, if such a human occupant is present. The output ofthe heartbeat sensor is input to the processor of the interiormonitoring system. One heartbeat sensor for use in the invention may beof the types as disclosed in McEwan (U.S. Pat. No. 5,573,012 and U.S.Pat. No. 5,766,208). The heartbeat sensor can be positioned at anyconvenient position relative to the seats where occupancy is beingmonitored. A preferred location is within the vehicle seat back.

An alternative way to determine the number of occupants is to monitorthe weight being applied to the seats, i.e., each seating location, byarranging weight sensors at each seating location which might also beable to provide a weight distribution of an object on the seat. Analysisof the weight and/or weight distribution by a predetermined method canprovide an indication of occupancy by a human, an adult or child, or aninanimate object.

Another type of sensor which is not believed to have been used in aninterior monitoring system heretofore is a micropower impulse radar(MIR) sensor which determines motion of an occupant and thus candetermine his or her heartbeat (as evidenced by motion of the chest).Such an MIR sensor can be arranged to detect motion in a particular areain which the occupant's chest would most likely be situated or could becoupled to an arrangement which determines the location of theoccupant's chest and then adjusts the operational field of the MIRsensor based on the determined location of the occupant's chest. Amotion sensor utilizing a micropower impulse radar (MIR) system isdisclosed, for example, in McEwan (U.S. Pat. No. 5,361,070), as well asmany other patents by the same inventor. Motion sensing is accomplishedby monitoring a particular range from the sensor, as disclosed in thatpatent. MIR is one form of radar which has applicability to occupantsensing and can be mounted at various locations in the vehicle. It hasan advantage over ultrasonic sensors in that data can be acquired at ahigher speed and thus the motion of an occupant can be more easilytracked. The ability to obtain returns over the entire occupancy rangeis somewhat more difficult than with ultrasound resulting in a moreexpensive system overall. MIR has additional advantages in lack ofsensitivity to temperature variation and has a comparable resolution toabout 40 kHz ultrasound. Resolution comparable to higher frequency isalso possible. Additionally, multiple MIR sensors can be used when highspeed tracking of the motion of an occupant during a crash is requiredsince they can be individually pulsed without interfering with eachthrough time division multiplexing.

An alternative way to determine motion of the occupant(s) is to monitorthe weight distribution of the occupant whereby changes in weightdistribution after an accident would be highly suggestive of movement ofthe occupant. A system for determining the weight distribution of theoccupants could be integrated or otherwise arranged in the right centerand left, front and back vehicle seats such as 343 and several patentsand publications describe such systems.

More generally, any sensor which determines the presence and healthstate of an occupant can also be integrated into the vehicle interiormonitoring system in accordance with the invention. For example, asensitive motion sensor can determine whether an occupant is breathingand a chemical sensor can determine the amount of carbon dioxide, or theconcentration of carbon dioxide, in the air in the vehicle which can becorrelated to the health state of the occupant(s). The motion sensor andchemical sensor can be designed to have a fixed operational fieldsituated where the occupant's mouth is most likely to be located. Inthis manner, detection of carbon dioxide in the fixed operational fieldcould be used as an indication of the presence of a human occupant inorder to enable the determination of the number of occupants in thevehicle. In the alternative, the motion sensor and chemical sensor canbe adjustable and adapted to adjust their operational field inconjunction with a determination by an occupant position and locationsensor which would determine the location of specific parts of theoccupant's body, e.g., his or her chest or mouth. Furthermore, anoccupant position and location sensor can be used to determine thelocation of the occupant's eyes and determine whether the occupant isconscious, i.e., whether his or her eyes are open or closed or moving.

The use of chemical sensors can also be used to detect whether there isblood present in the vehicle, for example, after an accident.Additionally, microphones can detect whether there is noise in thevehicle caused by groaning, yelling, etc., and transmit any such noisethrough the cellular or other communication connection to a remotelistening facility (such as operated by OnStar®).

FIG. 78 shows a schematic diagram of an embodiment of the inventionincluding a system for determining the presence and health state of anyoccupants of the vehicle and a telecommunications link. This embodimentincludes a system for determining the presence of any occupants 400which may take the form of a heartbeat sensor or motion sensor asdescribed above and a system for determining the health state of anyoccupants 401. The health state determining system may be integratedinto the system for determining the presence of any occupants, i.e., oneand the same component, or separate therefrom. Further, a system fordetermining the location, and optionally velocity, of the occupants orone or more parts thereof 402 are provided and may be any conventionaloccupant position sensor or preferably, one of the occupant positionsensors as described herein (e.g., those utilizing waves,electromagnetic radiation or electric fields) or as described in thecurrent assignee's patents and patent applications referenced above.

A processor 403 is coupled to the presence determining system 400, thehealth state determining system 401 and the location determining system402. A communications unit 404 is coupled to the processor 403. Theprocessor 403 and/or communications unit 404 can also be coupled tomicrophones 405 that can be distributed throughout the vehicle andinclude voice-processing circuitry to enable the occupant(s) to effectvocal control of the processor 403, communications unit 404 or anycoupled component or oral communications via the communications unit404. The processor 403 is also coupled to another vehicular system,component or subsystem 406 and can issue control commands to effectadjustment of the operating conditions of the system, component orsubsystem. Such a system, component or subsystem can be the heating orair-conditioning system, the entertainment system, an occupant restraintdevice such as an airbag, a glare prevention system, etc. Also, apositioning system 407 could be coupled to the processor 403 andprovides an indication of the absolute position of the vehicle,preferably using satellite-based positioning technology (e.g., a GPSreceiver).

In normal use (other than after a crash), the presence determiningsystem 400 determines whether any human occupants are present, i.e.,adults or children, and the location determining system 402 determinesthe occupant's location. The processor 403 receives signalsrepresentative of the presence of occupants and their location anddetermines whether the vehicular system, component or subsystem 406 canbe modified to optimize its operation for the specific arrangement ofoccupants. For example, if the processor 403 determines that only thefront seats in the vehicle are occupied, it could control the heatingsystem to provide heat only through vents situated to provide heat forthe front-seated occupants.

Another possible vehicular system, component or subsystem is anavigational aid, i.e., a route display or map. In this case, theposition of the vehicle as determined by the positioning system 407 isconveyed through processor 403 to the communications unit 404 to aremote facility and a map is transmitted from this facility to thevehicle to be displayed on the route display. If directions are needed,a request for the same could be entered into an input unit 408associated with the processor 403 and transmitted to the facility. Datafor the display map and/or vocal instructions could be transmitted fromthis facility to the vehicle.

Moreover, using this embodiment, it is possible to remotely monitor thehealth state of the occupants in the vehicle and most importantly, thedriver. The health state determining system 401 may be used to detectwhether the driver's breathing is erratic or indicative of a state inwhich the driver is dozing off. The health state determining system 401could also include a breath-analyzer to determine whether the driver'sbreath contains alcohol. In this case, the health state of the driver isrelayed through the processor 403 and the communications unit 404 to theremote facility and appropriate action can be taken. For example, itwould be possible to transmit a command (from the remote facility) tothe vehicle to activate an alarm or illuminate a warning light or if thevehicle is equipped with an automatic guidance system and ignitionshut-off, to cause the vehicle to come to a stop on the shoulder of theroadway or elsewhere out of the traffic stream. The alarm, warninglight, automatic guidance system and ignition shut-off are thusparticular vehicular components or subsystems represented by 406.

In use after a crash, the presence determining system 400, health statedetermining system 401 and location determining system 402 can obtainreadings from the passenger compartment and direct such readings to theprocessor 403. The processor 403 analyzes the information and directs orcontrols the transmission of the information about the occupant(s) to aremote, manned facility. Such information would include the number andtype of occupants, i.e., adults, children, infants, whether any of theoccupants have stopped breathing or are breathing erratically, whetherthe occupants are conscious (as evidenced by, e.g., eye motion), whetherblood is present (as detected by a chemical sensor) and whether theoccupants are making noise. Moreover, the communications link throughthe communications unit 404 can be activated immediately after the crashto enable personnel at the remote facility to initiate communicationswith the vehicle.

An occupant sensing system can also involve sensing for the presence ofa living occupant in a trunk of a vehicle or in a closed vehicle, forexample, when a child is inadvertently left in the vehicle or enters thetrunk and the trunk closes. To this end, a SAW-based chemical sensor 410is illustrated in FIG. 79A for mounting in a vehicle trunk asillustrated in FIG. 79. The chemical sensor 410 is designed to measurecarbon dioxide concentration through the mass loading effects asdescribed in U.S. Pat. No. 4,895,017 with a polymer coating selectedthat is sensitive to carbon dioxide. The speed of the surface acousticwave is a function of the carbon dioxide level in the atmosphere.Section 412 of the chemical sensor 410 contains a coating of such apolymer and the acoustic velocity in this section is a measure of thecarbon dioxide concentration. Temperature effects are eliminated througha comparison of the sonic velocities in sections 412 and 411 asdescribed above.

Thus, when the trunk lid 409 is closed and a source of carbon dioxidesuch as a child or animal is trapped within the trunk, the chemicalsensor 410 will provide information indicating the presence of thecarbon dioxide producing object to the interrogator which can thenrelease a trunk lock permitting the trunk lid 409 to automatically open.In this manner, the problem of children and animals suffocating inclosed trunks is eliminated. Alternately, information that a person oranimal is trapped in a trunk can be sent by the telematics system to lawenforcement authorities or other location or facility remote from thevehicle.

A similar device can be distributed at various locations within thepassenger compartment of vehicle along with a combined temperaturesensor. If the car has been left with a child or other animal whileowner is shopping, for example, and if the temperature rises within thevehicle to an unsafe level or, alternately, if the temperature dropsbelow an unsafe level, then the vehicle can be signaled to takeappropriate action which may involve opening the windows or starting thevehicle with either air conditioning or heating as appropriate.Alternately, information that a person or animal is trapped within avehicle can be sent by the telematics system to law enforcementauthorities or other location remote from the vehicle. Thus, throughthese simple wireless powerless sensors, the problem of suffocationeither from lack of oxygen or death from excessive heat or cold can allbe solved in a simple, low-cost manner through using an interrogator asdisclosed in the current assignee's U.S. patent application Ser. No.10/079,065.

A similar device can be distributed at various locations within thepassenger compartment of vehicle along with a combined temperaturesensor. If the car has been left with a child or other animal while theowner is shopping, for example, and if the temperature rises within thevehicle to an unsafe level or, alternately, if the temperature dropsbelow an unsafe level, then the vehicle can be signaled to takeappropriate action, which may involve opening the windows or startingthe vehicle with either air conditioning or heating as appropriate.Alternately, information that a person or animal is trapped within avehicle can be sent by the telematics system to law enforcementauthorities or another location remote from the vehicle. Thus, throughthese simple wireless powerless sensors, the problem of suffocationeither from lack of oxygen or death from excessive heat or cold can allbe solved in a simple, low-cost manner through using an interrogator asdisclosed in U.S. Pat. No. 6,662,642.

The operating conditions of the vehicle can also be transmitted alongwith the status of the occupants to a remote monitoring facility. Theoperating conditions of the vehicle include whether the motor is runningand whether the vehicle is moving. Thus, in a general embodiment inwhich information on both occupancy of the vehicle and the operatingconditions of the vehicle are transmitted, one or more properties orcharacteristics of occupancy of the vehicle are determined, suchconstituting information about the occupancy of the vehicle, and one ormore states of the vehicle or of a component of the vehicle isdetermined, such constituting information about the operation of thevehicle. The information about the occupancy of the vehicle andoperation of the vehicle are selectively transmitted, possibly theinformation about occupancy to an emergency response center and theinformation about the vehicle to a dispatcher, a dealer or repairfacility and/or the vehicle manufacturer.

Transmission of the information about the operation of the vehicle,i.e., diagnostic information, may be achieved via a satellite and/or viathe Internet. The vehicle would thus include appropriate electronichardware and/or software to enable the transmission of a signal to asatellite, from where it could be re-transmitted to a remote location(for example via the Internet), and/or to enable the transmission to aweb site or host computer. In the latter case, the vehicle could beassigned a domain name or e-mail address for identification ortransmission origination purposes.

The diagnostic discussion above has centered on notifying the vehicleoperator of a pending problem with a vehicle component. Today, there isgreat competition in the automobile marketplace and the manufacturersand dealers who are most responsive to customers are likely to benefitby increased sales both from repeat purchasers and new customers. Thediagnostic module disclosed herein benefits the dealer by making himinstantly aware, through the cellular telephone system, or othercommunication link, coupled to the diagnostic module or system inaccordance with the invention, when a component is likely to fail. Asenvisioned when the diagnostic module 33 detects a potential failure itnot only notifies the driver through a display 34 (as shown in FIGS. 3and 4), but also automatically notifies the dealer through a vehiclecellular phone 32 or other telematics communication link such as theinternet via satellite or Wi-Fi. The dealer can thus contact the vehicleowner and schedule an appointment to undertake the necessary repair ateach party's mutual convenience. Contact by the dealer to the vehicleowner can occur as the owner is driving the vehicle, using acommunications device. Thus, the dealer can contact the driver andinform him of their mutual knowledge of the problem and discussscheduling maintenance to attend to the problem. The customer is pleasedsince a potential vehicle breakdown has been avoided and the dealer ispleased since he is likely to perform the repair work. The vehiclemanufacturer also benefits by early and accurate statistics on thefailure rate of vehicle components. This early warning system can reducethe cost of a potential recall for components having design defects. Itcould even have saved lives if such a system had been in place duringthe Firestone tire failure problem mentioned above. The vehiclemanufacturer will thus be guided toward producing higher qualityvehicles thus improving his competitiveness. Finally, experience withthis system will actually lead to a reduction in the number of sensorson the vehicle since only those sensors that are successful inpredicting failures will be necessary.

For most cases, it is sufficient to notify a driver that a component isabout to fail through a warning display. In some critical cases, actionbeyond warning the driver may be required. If, for example, thediagnostic module detected that the alternator was beginning to fail, inaddition to warning the driver of this eventuality, the diagnosticsystem could send a signal to another vehicle system to turn off allnon-essential devices which use electricity thereby conservingelectrical energy and maximizing the time and distance that the vehiclecan travel before exhausting the energy in the battery. Additionally,this system can be coupled to a system such as OnStar® or a vehicleroute guidance system, and the driver can be guided to the nearest openrepair facility or a facility of his or her choice.

FIG. 80 shows a schematic of the integration of the occupant sensingwith a telematics link and the vehicle diagnosis with a telematics link.As envisioned, the occupant sensing system 415 includes those componentswhich determine the presence, position, health state, and otherinformation relating to the occupants, for example the transducersdiscussed above with reference to FIGS. 68 and 69 and the SAW devicediscussed above with reference to FIG. 79. Information relating to theoccupants includes information as to what the driver is doing, talkingon the phone, communicating with OnStar®, the internet or other routeguidance, listening to the radio, sleeping, drunk, drugged, having aheart attack, etc. The occupant sensing system may also be any of thosesystems and apparatus described in any of the current assignee'sabove-referenced patents and patent applications or any other comparableoccupant sensing system which performs any or all of the same functionsas they relate to occupant sensing. Examples of sensors which might beinstalled on a vehicle and constitute the occupant sensing systeminclude heartbeat sensors, motion sensors, weight sensors, ultrasonicsensors, MIR sensors, microphones and optical sensors.

A crash sensor 416 is provided and determines when the vehicleexperiences a crash. Crash sensor 416 may be any type of crash sensor.

Vehicle sensors 417 include sensors which detect the operatingconditions of the vehicle such as those sensors discussed with referenceto FIG. 79 and others above. Also included are tire sensors such asdisclosed in U.S. Pat. No. 6,662,642. Other examples include velocityand acceleration sensors, and angular and angular rate pitch, roll andyaw sensors or an IMU. Of particular importance are sensors that tellwhat the car is doing: speed, skidding, sliding, location, communicatingwith other cars or the infrastructure, etc.

Environment sensors 418 include sensors which provide data concerningthe operating environment of the vehicle, e.g., the inside and outsidetemperatures, the time of day, the location of the sun and lights, thelocations of other vehicles, rain, snow, sleet, visibility (fog),general road condition information, pot holes, ice, snow cover, roadvisibility, assessment of traffic, video pictures of an accident eitherinvolving the vehicle or another vehicle, etc. Possible sensors includeoptical sensors which obtain images of the environment surrounding thevehicle, blind spot detectors which provide data on the blind spot ofthe driver, automatic cruise control sensors that can provide images ofvehicles in front of the host vehicle, and various radar and lidardevices which provide the position of other vehicles and objectsrelative to the subject vehicle.

The occupant sensing system 415, crash sensors 416, vehicle sensors 417,and environment sensors 418 can all be coupled to a communicationsdevice 419 which may contain a memory unit and appropriate electricalhardware to communicate with all of the sensors, process data from thesensors, and transmit data from the sensors. The memory unit could beuseful to store data from the sensors, updated periodically, so thatsuch information could be transmitted at set time intervals.

The communications device 419 can be designed to transmit information toany number of different types of facilities. For example, thecommunications device 419 could be designed to transmit information toan emergency response facility 420 in the event of an accident involvingthe vehicle. The transmission of the information could be triggered by asignal from the crash sensor 416 that the vehicle was experiencing acrash or had experienced a crash. The information transmitted could comefrom the occupant sensing system 415 so that the emergency responsecould be tailored to the status of the occupants. For example, if thevehicle was determined to have ten occupants, more ambulances might besent than if the vehicle contained only a single occupant. Also, if theoccupants are determined not be breathing, then a higher priority callwith living survivors might receive assistance first. As such, theinformation from the occupant sensing system 415 could be used toprioritize the duties of the emergency response personnel.

Information from the vehicle sensors 417 and environment sensors 418could also be transmitted to law enforcement authorities 422 in theevent of an accident so that the cause(s) of the accident could bedetermined. Such information can also include information from theoccupant sensing system 415, which might reveal that the driver wastalking on the phone, putting on make-up, or another distractingactivity, information from the vehicle sensors 417 which might reveal aproblem with the vehicle, and information from the environment sensors418 which might reveal the existence of slippery roads, dense fog andthe like.

Information from the occupant sensing system 415, vehicle sensors 417and environment sensors 418 could also be transmitted to the vehiclemanufacturer 423 in the event of an accident so that a determination canbe made as to whether failure of a component of the vehicle caused orcontributed to the cause of the accident. For example, the vehiclesensors might determine that the tire pressure was too low so thatadvice can be disseminated to avoid maintaining the tire pressure toolow in order to avoid an accident. Information from the vehicle sensors417 relating to component failure could be transmitted to adealer/repair facility 421 which could schedule maintenance to correctthe problem.

The communications device 419 could be designed to transmit particularinformation to each site, i.e., only information important to beconsidered by the personnel at that site. For example, the emergencyresponse personnel have no need for the fact that the tire pressure wastoo low but such information is important to the law enforcementauthorities 422 (for the possible purpose of issuing a recall of thetire and/or vehicle) and the vehicle manufacturer 423.

The communication device can be a cellular phone, DSRC, OnStar®, orother subscriber-based telematics system, a peer-to-peer vehiclecommunication system that eventually communicates to the infrastructureand then, perhaps, to the Internet with e-mail or instant message to thedealer, manufacturer, vehicle owner, law enforcement authorities orothers. It can also be a vehicle to LEO or Geostationary satellitesystem such as SkyBitz which can then forward the information to theappropriate facility either directly or through the Internet or a directconnection to the internet through a satellite or 802.11 Wi-Fi link orequivalent.

The communication may need to be secret so as not to violate the privacyof the occupants and thus encrypted communication may, in many cases, berequired. Other innovations described herein include the transmission ofany video data from a vehicle to another vehicle or to a facility remotefrom the vehicle by any means such as a telematics communication systemsuch as DSRC, OnStar®, a cellular phone system, a communication via GEO,geocentric or other satellite system and any communication thatcommunicates the results of a pattern recognition system analysis. Also,any communication from a vehicle can combine sensor information withlocation information.

When optical sensors are provided as part of the occupant sensing system415, video conferencing becomes a possibility, whether or not thevehicle experiences a crash. That is, the occupants of the vehicle canengage in a video conference with people at another location 424 viaestablishment of a communications channel by the communications device419.

The vehicle diagnostic system described above using a telematics linkcan transmit information from any type of sensors on the vehicle.

In one particular use of the invention, a wireless sensing andcommunication system is provided whereby the information or dataobtained through processing of input from sensors of the wirelesssensing and communication system is further transmitted for reception bya remote facility. Thus, in such a construction, there is anintra-vehicle communications between the sensors on the vehicle and aprocessing system (control module, computer or the like) and remotecommunications between the same or a coupled processing system (controlmodule, computer or the like). The electronic components for theintra-vehicle communication may be designed to transmit and receivesignals over short distances whereas the electronic components whichenable remote communications should be designed to transmit and receivesignals over relatively long distances.

The wireless sensing and communication system includes sensors that arelocated on the vehicle or in the vicinity of the vehicle and whichprovide information which is transmitted to one or more interrogators inthe vehicle by wireless radio frequency means, using wireless radiofrequency transmission technology. In some cases, the power to operate aparticular sensor is supplied by the interrogator while in other cases,the sensor is independently connected to either a battery, generator(piezo electric, solar etc.), vehicle power source or some source ofpower external to the vehicle.

One particular system requires mentioning which is the use of high speedsatellite or Wi-Fi internet service such as supplied by Wi-Fi hot spotsor KVH Industries, Inc. for any and all vehicle communications includingvehicle telephone, TV and radio services. With thousands of radiostations available over the internet, for example (see shoutcast.com), ahigh speed internet connection is clearly superior to satellite radiosystems that are now being marketed. Similarly, with ubiquitous internetaccess that KVH supplies throughout the country, the lack of coverageproblems with cell phones disappears. This capability becomesparticularly useful for emergency notification when a vehicle has anaccident or becomes disabled.

2.2 Docking Stations and PDAs

There is a serious problem developing with vehicles such as cars,trucks, boats and private planes and computer systems. The quality andlifetime of vehicles is increasing and now many vehicles have a lifetimethat exceeds ten or more years. On the other hand, computer and relatedelectronic systems, which are proliferating on such vehicles, haveshorter and shorter life spans as they are made obsolete by theexponential advances in technology. Owners do not want to dispose oftheir vehicles just because the electronics have become obsolete.Therefore, a solution as proposed in this invention, whereby asubstantial portion of the information, programs, processing power andmemory are separate from the vehicle, will increasingly becomenecessary. One implementation of such a system is for the information,programs, processing power and memory to be resident in a portabledevice that can be removed from the vehicle. Once removed, the vehiclemay still be operable but with reduced functionality. The navigationsystem, for example, may be resident on the removable device whichhereinafter will be referred to as a Personal Information Device (PID)including a GPS subsystem and perhaps an IMU along with appropriate mapsallowing a person to navigate on foot as well as in the vehicle. Thetelephone system which can be either internet or cell phone-based and ifinternet-based, can be a satellite internet, Wi-Fi or equivalent systemwhich could be equally operable in a vehicle or on foot. The softwaredata and programs can be kept updated including all of the software fordiagnostic functions, for example, for the vehicle through the internetconnection. The vehicle could contain supplemental displays (such as aheads-up display), input devices including touch pads, switches, voicerecognition and cameras for occupant position determination and gesturerecognition, and other output devices such as speakers, warning lightsetc., for example.

As computer hardware improves it can be an easy step for the owner toreplace the PID with the latest version which may even be supplied tothe owner under subscription by the Cell Phone Company, car dealership,vehicle manufacturer, computer manufacturer etc. Similarly, the samedevice can be used to operate the home computer system or entertainmentsystem. In other words, the owner would own one device, the PID, whichwould contain substantially all of the processing power, software andinformation that the owner requires to operate his vehicles, computersystems etc. The system can also be periodically backed up (perhaps alsoover the Internet), automatically providing protection against loss ofdata in the event of a system failure. The PID can also have abiometrics-based identification system (fingerprint, voiceprint, face oriris recognition etc.) that prevents unauthorized users from using thesystem and an automatic call back location system based on GPS or otherlocation technologies that permits the owner to immediately find thelocation of the PID in the event of misplacement or theft.

The PID can also be the repository of credit card information permittinginstant purchases without the physical scanning of a separate creditcard, home or car door identification system to eliminate keys andconventional keyless entry systems, and other information of a medicalnature to aid emergency services in the event of a medical emergency.The possibilities are limitless for such a device. A PID, for example,can be provided with sensors to monitor the vital functions of anelderly person and signal if a problem occurs. The PID can be programmedand provided with sensors to sense fire, cold, harmful chemicals orvapors, biological agents (such as smallpox or anthrax) for use in avehicle or any other environment. An automatic phone call, or othercommunication, can be initiated when a hazardous substance (or any otherdangerous or hazardous situation or event) is detected to inform theauthorities along with the location of the PID. Since the PID would haveuniversal features, it could be taken from vehicle to vehicle allowingeach person to have personal features in whatever vehicle he or she wasoperating. This would be useful for rental vehicles, for example, seats,mirrors, radio stations, HVAC can be automatically set for the PIDowner. The same feature can apply to offices, homes, etc.

The same PID can also be used to signal the presence of a particularperson in a room and thereby to set the appropriate TV or radiostations, room temperature, lighting, wall pictures etc. For example,the PID could also assume the features of a remote when a person iswatching TV. A person could of course have more than one PID and a PIDcould be used by more than one person provided a means of identificationis present such as a biometric based ID or password system. Thus, eachindividual would need to learn to operate one device, the PID, insteadof multiple devices. The PID could even be used to automatically unlockand initiate some action such as opening a door or turning on lights ina vehicle, house, apartment or building. Naturally, the PID can have avariety of associated sensors as discussed above including cameras,microphones, accelerometers, an IMU, GPS receiver, Wi-Fi receiver etc.

Other people could also determine the location of a person carrying thePID, if such a service is authorized by the PID owner. In this manner,parents can locate their children or friends can locate each other in acrowded restaurant or airport. The location or tracking information canbe made available on the Internet through the Skybitz or similar lowpower tracking system. Also, the batteries that operate the PID can berecharged in a variety of ways including fuel cells and vibration-basedpower generators, solar power, induction charging systems etc. Forfurther background, see N. Tredennick “031201 Go Reconfigure”, IEEESpectrum Magazine, p. 37-40, December 2003 and D. Verkest “MachineCameleon” ibid p. 41-46, which describe some of the non-vehicle relatedproperties envisioned here for the PID. Also for some automotiveapplications see P. Hansen “Portable electronics threaten embeddedelectronics”, Automotive Industries Magazine, December 2004. Such adevice could also rely heavily on whatever network it had access to whenit is connected to a network such as the Internet. It could use theconnected network for many processing tasks which exceed the capabilityof the PID or which require information that is not PID-resident. In asense, the network can become the computer for these more demandingtasks. Using the Internet as the computer gives the automobile companiesmore control over the software and permits a pricing model based on userather than a one time sale. Such a device can be based onmicroprocessors, FPGAs or programmable logical devices or a combinationthereof. This is the first disclosure of vehicular uses of such a deviceto solve the mismatched lifetimes of the vehicle and its electronichardware and software as discussed above.

When brought into a vehicle, the PID can connect (either by a wire ofwirelessly using Bluetooth, Zigbee or 802.11 protocols, for example) tothe vehicle system and make use of resident displays, audio systems,antennas and input devices. In this case, the display can be a heads-updisplay (HUD) and the input devices can be by audio, manual switches,touchpad, joystick, or cameras as disclosed in section 4 and elsewhereherein.

2.3 Satellite and Wi-Fi Internet

Ultimately vehicles will be connected to the Internet with a high speedconnection. Such a connection will still be too slow forvehicle-to-vehicle communications for collision avoidance purposes butit should be adequate for most other vehicle communication purposes.Such a system will probably obsolete current cell phone systems andsubscriber systems such as OnStar™. Each user can have a singleidentification number (which could be his or her phone number) whichlocates his or her address, phone number, current location etc. Thevehicle navigation system can guide the vehicle to the location based onthe identification number without the need to input the actual address.

The ubiquitous Internet system could be achieved by a fleet of low earthorbiting satellites (LEOs) or transmission towers transmitting andreceiving signals based on one of the 802.11 protocols having a radialrange of 50 miles, for example. Thus, approximately 500 such towerscould cover the continental United States.

A high speed Internet connection can be used for software upgradedownloading and for map downloading as needed. Each vehicle can become aprobe vehicle that locates road defects such as potholes, monitorstraffic and monitors weather and road conditions. It can also monitorfor terrorist activities such as the release of chemical or biologicalagents as well as provide photographs of anomalies such as trafficaccidents, mud slides or fallen trees across the road, etc., any or allof this information can be automatically fed to the appropriate IPaddress over the Internet providing for ubiquitous information gatheringand dissemination. The same or similar system can be available on othervehicles such as planes, trains, boats, trucks etc.

Today, high speed Internet access is available via GEO satellite tovehicles using the KVH system. It is expected that more and more citieswill provide citywide internet services via 802.11 systems includingWi-Fi, Wi-Max and Wi-Mobile or their equivalents. Eventually, it isexpected that such systems will be available in rural areas thus makingthe Internet available nationwide and eventually worldwide through oneor a combination of satellite and terrestrial systems. Although the KVHsystem is based on GEO satellites, it is expected that eventually LEOsatellites will offer a similar service at a lower price and requiring asmaller antenna. Such an antenna will probably be based on phase arraytechnology.

3.0 Wiring and Busses

In the discussion above, the diagnostic module of this invention assumesthat a vehicle data bus exists which is used by all of the relevantsensors on the vehicle. Most vehicles today do not have a data busalthough it is widely believed that most vehicles will have one in thefuture. In lieu of such a bus, the relevant signals can be transmittedto the diagnostic module through a variety of coupling systems otherthan through a data bus and this invention is not limited to vehicleshaving a data bus. For example, the data can be sent wirelessly to thediagnostic module using the Bluetooth™, ZIGBEE or 802.11 or similarspecification. In some cases, even the sensors do not have to be wiredand can obtain their power via RF from the interrogator as is well knownin the RFID radio frequency identification field (either silicon orsurface acoustic wave (SAW)-based)). Alternately, an inductive orcapacitive power transfer system can be used.

Several technologies have been described above all of which have theobjective of improving the reliability and reducing the complexity ofthe wiring system in an automobile and particularly the safety system.Most importantly, the bus technology described has as its objectivesimplification and increase in reliability of the vehicle wiring system.The safety system wiring was first conceived of as a method forpermitting the location of airbag crash sensors at locations where theycan most effectively sense a vehicle crash and yet permit thatinformation to be transmitted to the airbag control circuitry which maybe located in a protected portion of the interior of the vehicle or mayeven be located on the airbag module itself. Protecting thistransmission requires a wiring system that is far more reliable andresistant to being destroyed in the very crash that the sensor issensing. This led to the realization that the data bus that carries theinformation from the crash sensor must be particularly reliable. Upondesigning such a data bus, however, it was found that the capacity ofthat data bus far exceeded the needs of the crash sensor system. Thisthen led to a realization that the capacity, or bandwidth, of such a buswould be sufficient to carry all of the vehicle informationrequirements. In some cases, this requires the use of high bandwidth bustechnology such as twisted pair wires, shielded twisted pair wires, orcoax cable. If a subset of all of the vehicle devices is included on thebus, then the bandwidth requirements are less and simpler bustechnologies can be used instead of a coax cable, for example. Theeconomics that accompany a data bus design which has the highestreliability, highest bandwidth, is justified if all of the vehicledevices use the same system. This is where the greatest economies andgreatest reliability occur. As described above, this permits, forexample, the placement of the airbag firing electronics into or adjacentthe housing that contains the airbag inflator. Once the integrity of thedata bus is assured, such that it will not be destroyed during the crashitself, then the proper place for the airbag intelligence can be in, oradjacent to, the airbag module itself. This further improves thereliability of the system since the shorting of the wires to the airbagmodule will not inadvertently set off the airbag as has happenedfrequently in the past.

When operating on the vehicle data bus, each device should have a uniqueaddress. For most situations, therefore, this address must bepredetermined and then assigned through an agreed-upon standard for allvehicles. Thus, the left rear tail light must have a unique address sothat when the turn signal is turned to flash that light, it does notalso flash the right tail light, for example. Similarly, the side impactcrash sensor which will operate on the same data bus as the frontalimpact crash sensor, must issue a command, directly or indirectly, tothe side impact airbag and not to the frontal impact airbag.

One of the key advantages of a single bus system connecting all sensorsin the vehicle together is the possibility of using this data bus todiagnose the health of the entire safety system or of the entirevehicle, as described in the detail above. Thus, there are clearsynergistic advantages to all the disparate technologies describedabove.

The design, construction, installation, and maintenance a vehicle databus network requires attention to many issues, including: an appropriatecommunication protocol, physical layer transceivers for the selectedmedia, capable microprocessors for application and protocol execution,device controller hardware and software for the required sensors andactuators, etc. Such activities are known to those skilled in the artand will not be described in detail here.

An intelligent distributed system as described above can be based on theCAN Protocol, for example, which is a common protocol used in theautomotive industry. CAN is a full function network protocol thatprovides both message checking and correction to insure communicationintegrity. Many of the devices on the system will have their own specialdiagnostics. For instance, an inflator control system can send a warningmessage if its backup power supply has insufficient charge. In order toassure the integrity and reliability of the bus system, most deviceswill be equipped with bi-directional communication as described above.Thus, when a message is sent to the rear right taillight to turn on, thelight can return a message that it has executed the instruction.

In a refinement of this embodiment, more of the electronics associatedwith the airbag system can be decentralized and housed within or closelyadjacent to each of the airbag modules. Each module can have its ownelectronic package containing a power supply and diagnostic andsometimes also the occupant sensor electronics. One sensor system isstill used to initiate deployment of all airbags associated with thefrontal impact. To avoid the noise effects of all airbags deploying atthe same time, each module sometimes has its own delay. The modules forthe rear seat, for example, can have a several millisecond firing delaycompared with the module for the driver and the front passenger modulecan have a lesser delay. Each of the modules can also have its ownoccupant position sensor and associated electronics. In thisconfiguration, there is a minimum reliance on the transmission of powerand data to and from the vehicle electrical system which is the leastreliable part of the airbag system, especially during a crash. Once eachof the modules receives a signal from the crash sensor system, it is onits own and no longer needs either power or information from the otherparts of the system. The main diagnostics for a module can also residewithin the module which transmits either a ready or a fault signal tothe main monitoring circuit which now needs only to turn on a warninglight, and perhaps record the fault, if any of the modules either failsto transmit a ready signal or sends a fault signal.

Thus, the placement of electronic components in or near the airbagmodule can be important for safety and reliability reasons. Theplacement of the occupant sensing as well as the diagnostics electronicswithin or adjacent to the airbag module has additional advantages tosolving several current important airbag problems. For example, therehave been numerous inadvertent airbag deployments caused by wires in thesystem becoming shorted. Then, when the vehicle hits a pothole, which issufficient to activate an arming sensor or otherwise disturb the sensingsystem, the airbag can deploy. Such an unwanted deployment of course candirectly injure an occupant who is out-of-position or cause an accidentresulting in occupant injuries. If the sensor were to send a codedsignal to the airbag module rather than a DC voltage with sufficientpower to trigger the airbag, and if the airbag module had stored withinits electronic circuit sufficient energy to initiate the inflator, thenthese unwanted deployments could be prevented. A shorted wire cannotsend a coded signal and the short can be detected by the module residentdiagnostic circuitry.

This would require that the airbag module contain, or have adjacent toit, a power supply (formerly the backup power supply) which furtherimproves the reliability of the system since the electrical connectionto the sensor, or to the vehicle power, can now partially fail, as mighthappen during an accident, and the system will still work properly. Itis well known that the electrical resistance in the “clockspring”connection system, which connects the steering wheel-mounted airbagmodule to the sensor and diagnostic system, has been marginal in designand prone to failure. The resistance of this electrical connection mustbe very low or there will not be sufficient power to reliably initiatethe inflator squib. To reduce the resistance to the level required, highquality gold-plated connectors are preferably used and the wires shouldalso be of unusually high quality. Due to space constraints, however,these wires frequently have only a marginally adequate resistancethereby reducing the reliability of the driver airbag module andincreasing its cost. If, on the other hand, the power to initiate theairbag were already in the module, then only a coded signal needs to besent to the module rather than sufficient power to initiate theinflator. Thus, the resistance problem disappears and the modulereliability is increased. Additionally, the requirements for theclockspring wires become less severe and the design can be relaxedreducing the cost and complexity of the device. It may even be possibleto return to the slip ring system that existed prior to theimplementation of airbags.

Under this system, the power supply can be charged over a few seconds,since the power does not need to be sent to the module at the time ofthe required airbag deployment because it is already there. Thus, all ofthe electronics associated with the airbag system except the sensor andits associated electronics, if any, could be within or adjacent to theairbag module. This includes optionally the occupant sensor, thediagnostics and the (backup) power supply, which now becomes the primarypower supply, and the need for a backup disappears. When a fault isdetected, a message is sent to a display unit located typically in theinstrument panel.

The placement of the main electronics within each module follows thedevelopment path that computers themselves have followed from a largecentralized mainframe base to a network of microcomputers. The computingpower required by an occupant position sensor, airbag system diagnosticsand backup power supply can be greater than that required by a singlepoint sensor or of a sensor system employing satellite sensors. For thisreason, it can be more logical to put this electronic package within oradjacent to each module. In this manner, the advantages of a centralizedsingle point sensor and diagnostic system fade since most of theintelligence will reside within or adjacent to the individual modulesand not the centralized system. A simple and more effective CrushSwitchsensor such as disclosed in U.S. Pat. No. 5,441,301, for example, nowbecomes more cost effective than the single point sensor and diagnosticsystem which is now being widely adopted. Finally, this also isconsistent with the migration to a bus system where the power andinformation are transmitted around the vehicle on a single bus systemthereby significantly reducing the number of wires and the complexity ofthe vehicle wiring system. The decision to deploy an airbag is sent tothe airbag module sub-system as a signal not as a burst of power.Although it has been assumed that the information would be sent over awire bus, it is also possible to send the deploy command by a variety ofwireless methods either using wires or wirelessly.

A partial implementation of the system as just described is depictedschematically in FIG. 81 which shows a view of the combination of anoccupant position sensor and airbag module designed to prevent thedeployment of the airbag for a seat which is unoccupied or if theoccupant is too close to the airbag and therefore in danger ofdeployment-induced injury. The module, shown generally at 430, includesa housing which comprises an airbag 431, an inflator assembly 432 forthe airbag 431, an occupant position sensor comprising an ultrasonictransmitter 433 and an ultrasonic receiver 434. Other occupant positionsensors can also be used instead of the ultrasonic transmitter/receiverpair to determine the position of the occupant to be protected by theairbag 431, and also the occupant position sensor (433,434) may belocated outside of the housing of the module 430. A preferredalternative occupant sensor system uses a camera as disclosed in severalof the assignee's patents such as U.S. Pat. No. 5,748,473, U.S. Pat. No.5,835,613, U.S. Pat. No. 6,141,432, U.S. Pat. No. 6,270,116, U.S. Pat.No. 6,324,453 and U.S. Pat. No. 6,856,873. In the ultrasonic example,the housing of the module 430 also can contain an electronic module orpackage 435 coupled to each of the inflator assembly 432, thetransmitter 433 and the receiver 434 and which performs the functions ofsending the ultrasonic signal to the transmitter 433 and processing thedata from the occupant position sensor receiver 434. Electronics module435 may be arranged within the housing of the module 430 as shown oradjacent or proximate the housing of the module 430. Module 430 can alsocontain a power supply (not shown) for supplying power upon command bythe electronics module 435 to the inflator assembly 432 to causeinflation of the airbag 431. Thus, electronics module 435 controls theinflation or deployment of the airbag 431 and may sometimes herein bereferred to as a controller or control unit. In addition, the electronicmodule 435 can monitor the power supply voltage, to assure thatsufficient energy is stored to initiate the inflator assembly 432 whenrequired, and power the other processes, and can report periodicallyover the vehicle bus 436 to the central diagnostic module, shownschematically at 437, to indicate that the module is ready, i.e., thereis sufficient power of inflate or deploy the airbag 431 and operate theoccupant position sensor transmitter/receiver pair 433, 434, or sends afault code if a failure in any component being monitored has beendetected. A CrushSwitch sensor is also shown schematically at 438, whichcan be the only discriminating sensor in the system. Sensor 438 iscoupled to the vehicle bus 436 and can transmit a coded signal over thebus to the electronics module 435 to cause the electronics module 435 toinitiate deployment of the airbag 431 via the inflator assembly 432. Thevehicle bus 436 connects the electronic package 435, the central sensorand diagnostic module 437 and the CrushSwitch sensor 438. Bus 436 may bethe single bus system, i.e., consists of a pair of wires, on which powerand information are transmitted around the vehicle as noted immediatelyabove. Instead of CrushSwitch sensor 438, other crash sensors may beused.

When several crash sensors and airbag modules are present in thevehicle, they can all be coupled to the same bus or discrete portions ofthe airbag modules and crash sensors can be coupled to separate buses.Other ways for connecting the crash sensors and airbag modules to anelectrical bus can also be implemented in accordance with the inventionsuch as connecting some of the sensors and/or modules in parallel to abus and others daisy-chained onto the bus. This type of bus architectureis described in U.S. Pat. No. 6,212,457.

It should be understood that airbag module 430 is a schematicrepresentation only and thus, may represent any of the airbag modulesdescribed above in any of the mounting locations. For example, airbagmodule 430 may be arranged in connection with the seat 525 as module 510is in FIG. 82, as a side curtain airbag or as a passenger side airbag orelsewhere. For the seat example, the bus, which is connected to theairbag module 510, would inherently extend at least partially into andwithin the seat.

Another implementation of the invention incorporating the electroniccomponents into and adjacent to the airbag module as illustrated in FIG.83 which shows the interior front of the passenger compartment generallyat 445. Driver airbag module 446 is partially cutaway to show anelectronic module 447 incorporated within the airbag module 446.Electronic module 447 may be comparable to electronic module 435 in theembodiment of FIG. 8S in that it can control the deployment of theairbag in airbag module 446. Electronic airbag module 446 is connectedto an electronic sensor illustrated generally as 451 by a wire 448. Theelectronic sensor 451 can be, for example, an electronic single pointcrash sensor that initiates the deployment of the airbag when it sensesa crash. Passenger airbag module 450 is illustrated with its associatedelectronic module 452 outside of but adjacent or proximate to the airbagmodule. Electronic module 452 may be comparable to electronic module 439in the embodiment of FIG. 8S in that it can control the deployment ofthe airbag in airbag module 450. Electronic module 452 is connected by awire 449, which could also be part of a bus, to the electronic sensor451. One or both of the electronic modules 447 and 452 can containdiagnostic circuitry, power storage capability (either a battery or acapacitor), occupant sensing circuitry, as well as communicationelectronic circuitry for either wired or wireless communication.

It should be understood that although only two airbag modules 446,450are shown, it is envisioned that an automotive safety network may bedesigned with several and/or different types of occupant protectiondevices. Such an automotive network can comprise one or more occupantprotection devices connected to the bus, each comprising a housing and acomponent deployable to provide protection for the occupant, at leastone sensor system for providing an output signal relevant to deploymentof the deployable component(s) (such as the occupant sensing circuitry),a deployment determining system for generating a signal indicating forwhich of the deployable components deployment is desired (such as acrash sensor) and an electronic controller arranged in, proximate oradjacent each housing and coupled to the sensor system(s) and thedeployment determining system. The electrical bus electrically couplesthe sensor system(s), the deployment determining system and thecontrollers so that the signals from one or more of the sensor systemsand the deployment determining system are sent over the bus to thecontrollers. Each controller controls deployment of the deployablecomponent of the respective occupant protection device in considerationof the signals from the sensor system(s) and the deployment determiningsystem. The crash sensor(s) may be arranged separate and at a locationapart from the housings and generate a coded signal when deployment ofany one of the deployable components is desired. Thus, the coded signalvaries depending on which of deployment components are to be deployed.If the deployable component is an airbag associated with the housing,the occupant protection device would comprise an inflator assemblyarranged in the housing for inflating the airbag.

The safety bus, or any other vehicle bus, may use a coaxial cable. Aconnector for joining two coaxial cables 457 and 458 is illustrated inFIGS. 70A, 70B, 70C and 70D generally at 455. A cover 456 can behingeably attached to a base 459. A connector plate 461 can be slidablyinserted into base 459 and can contain two abrasion and connectionsections 463 and 464. A second connecting plate 465 can contain twoconnecting pins 462, one corresponding to each cable to be connected. Toconnect the two cables 457 and 458 together is this implementation, theyare first inserted into their respective holes 466 and 467 in base 459until they are engaged by pins 462. Sliding connector plate 461 is theninserted and cover 460 rotated pushing connector plate 461 downwarduntil the catch 468 snaps over mating catch 469. Other latching devicesare of course usable in accordance with the invention. During thisprocess, the serrated part 463 of connector plate 461 abrades theinsulating cover off of the outside of the respective cable exposing theouter conductor. The particle coated section 464 of connector plate 461then engages and makes electrical contact with the outer conductor ofthe coaxial cables 457 and 458. In this manner, the two coaxial cables457,458 are electrically connected together in a very simple manner.

Consider now various uses of a bus system.

3.1 Airbag Systems

The airbag system currently involves a large number of wires that carryinformation and power to and from the airbag central processing unit.Some vehicles have sensors mounted in the front of the vehicle and manyvehicles also have sensors mounted in the side structure (the door,B-Pillar, sill, or any other location that is rigidly connected to theside crush zone of the vehicle). In addition, there are sensors and anelectronic control module mounted in the passenger compartment. All carsnow have passenger and driver airbags and some vehicles have as many aseight airbags considering the side impact torso airbag and head airbagsas well as knee bolster airbags.

To partially cope with this problem, there is a movement to connect allof the safety systems onto a single bus (see for example U.S. Pat. No.6,326,704). Once again, the biggest problem with the reliability ofairbag systems is the wiring and connectors. By practicing the teachingsof this invention, one single pair of wires can be used to connect allof the airbag sensors and airbags together and, in one preferredimplementation, to do so without the use of connectors. Thus, thereliability of the system is substantially improved and the reducedinstallation costs more than offsets the added cost of having a looselycoupled inductive network, for example, described elsewhere herein.

With such a system, more and more of the airbag electronics can residewithin or adjacent to the airbag module with the crash sensor andoccupant information fed to the electronics modules for the deploydecision. Thus, all of the relevant information can reside on thevehicle safety or general bus with each airbag module making its owndeploy decision locally.

3.2 Steering Wheel

The steering wheel of an automobile is becoming more complex as morefunctions are incorporated utilizing switches and/or a touch pad, forexample, on the steering wheel or other haptic or non-haptic input oreven output devices. Many vehicles have controls for heating and airconditioning, cruise control, radio, etc.

Although previously not implemented, a steering can also be an outputdevice by causing various locations on the steering wheel to provide avibration, electrical shock or other output to the driver. This is incontrast to vibrating the entire steering wheel which has been proposedfor an artificial rumble strip application when a vehicle departs fromits lane. Such a local feedback can be used to identify for the driverwhich button he or she should press to complete an action such asdialing a phone number, for example (see H Kajimoto et al., SmartTouch:Electric Skin to Touch the Untouchable” IEEE Computer Graphics andApplications, pp 36-43, January-February, 2004, IEEE).

Additionally, the airbag must have a very high quality connection sothat it reliably deploys even when an accident is underway.

This has resulted in the use of clockspring ribbon cables that make allof the electrical connections between the vehicle and the rotatingsteering wheel. The ribbon cable must at least able to carry sufficientcurrent to reliably initiate airbag deployment even at very coldtemperatures. This requires that the ribbon cable contain at least twoheavy conductors to bring power to the airbag. Under the airbag networkconcept, a capacitor or battery can be used within the airbag module andkept charged thereby significantly reducing the amount of current thatmust pass through the ribbon cable. Thus, the ribbon cable can be keptconsiderably smaller, as discussed above.

An alternate and preferred solution uses the teachings of this inventionto inductively couple the steering wheel with the vehicle thuseliminating all wires and connectors. All of the switch functions,control functions, and airbag functions are multiplexed on top of theinductive carrier frequency. This greatly simplifies the initialinstallation of the steering wheel onto the vehicle since a complicatedribbon cable is no longer necessary. Similarly, it reduces warrantyrepairs caused by people changing steering wheels without making surethat the ribbon cable is properly positioned.

As described elsewhere herein, an input device such as a mouse pad, joystick or even one or more switches can be placed on the steering wheeland used to control a display such as a heads-up display thus permittingthe vehicle operator to control many functions of a vehicle withouttaking his or her eyes off of the road. BMW recently introduced the IPODhaptic interface which attempts to permit the driver to control manyvehicle functions (HVAC, etc.) but it lacks the display feedback andthus has been found confusing to vehicle operators. This problemdisappears when such a device is coupled with a display and particularlya heads-up display as taught herein. Although a preferred location forthe input device is the steering wheel, it can be placed at otherlocations in the vehicle as is the IPOD.

The use of a haptic device can be extended to give feedback to theoperator. If the phone rings, for example, a particular portion of thesteering wheel can be made to vibrate indicating where the operatorshould depress a switch to answer the phone. The display can alsoindicate to the driver that the phone is ringing and perhaps indicate tohim or her the location of the switch or that a oral command should begiven to answer the phone.

As one example of the implementation of this concept consider thefollowing description used in conjunction with FIGS. 71A-72. FIG. 71A isa front view of a steering wheel having two generalized switches locatedat 3 and 9 o'clock on the steering wheel rim. FIG. 71B is a view similarto FIG. 71A with the addition of a thumb switch option and FIG. 71C is arear view of the steering wheel of FIG. 71B with a finger triggeroption.

Starting with the assumptions that:

-   -   The driver should be able to control various systems in the        automobile without looking away from the road    -   The driver should be able to control these systems without        taking his/her hands away from the steering wheel    -   All system control interfaces fundamentally will be menu-driven    -   Some sort of cursor on a heads-up or other easily visible        display coupled with a mouse pad or joystick, as discussed        below, might be distracting, it would be better to simply        highlight and select from menu options.

Menus can easily be traversed with three buttons, one to move theselection up, one to move it down, and one to select. Since the drivershould keep his/her hands on the steering wheel at all times, thesebuttons, 801, 802 and 803 should be placed so they can be accessed atthe standard 3 o'clock and 9 o'clock hand positions.

Buttons could be placed on the front of the steering wheel such that thedriver's thumbs can press them, or probably better, buttons could beplaced on the rear of the steering wheel such that fingers could usethem as triggers.

To prevent accidental menu launch (which could be distracting), allthree buttons, 801, 802, and 803 could be pressed simultaneously tosummon the menu on the heads-up display, or some similar scheme could bedevised. If the driver presses on the brakes or makes a fast turn as anevasive maneuver, the menu can be designed to disappear so that thedriver is not distracted when driving requires his/her attention.

In FIGS. 71A, 71B and FIG. 72, the two button cluster, 801, 803(accessed by the left hand in the images, but side does not matter) canbe, for example, menu option up and menu option down. The single buttoncan be menu option select.

A press-knob could also be a good solution, but it has the disadvantagethat it can't be placed in the optimal steering wheel driving position(3 or 9). This concept is likely similar to the IPOD input device nowfound on some BMW's, namely, a rotary knob that when turned highlightsdifferent menu options and when pressed selects the currentlyhighlighted option. An advantage to this is that it is a betterinterface for temperature and volume controls in the car since it can besimply turned to adjust the parameter rather than pressed repeatedly, orpressed and held down as switches would be. This continuously varyingfunction can also be achieved with a scroll wheel. FIG. 72 illustratesthe addition of a mouse type scroll wheel 805 for the left hand.

Another solution would be a partial combination of the two. The menuitem select function could be implemented as a wheel 805, similar to thescroll wheel on modern computer mice. Option select could be implementedwith a wheel press or with a separate switch. The menu select wheelwould be thumb-accessible, and a select switch could be a finger triggerswitch.

All of the steering wheel mounted switched discussed above and below canbe wireless and powerless devices such as those discussed herein basedof RFID and SAW technologies.

3.3 Door Subsystem

More and more electrical functions are also being placed into vehicledoors. This includes window control switches and motors as well as seatcontrol switches, airbag crash sensors, etc. As a result the bundle ofwires that must pass through the door edge and through the A-pillar hasbecome a serious assembly and maintenance problem in the automotiveindustry. Using the teachings of this invention, a loosely coupledinductive system could pass anywhere near the door and an inductivepickup system placed on the other side where it obtains power andexchanges information when the mating surfaces are aligned. If thesesurfaces are placed in the A-pillar, then sufficient power can beavailable even when the door is open. Alternately, a battery orcapacitive storage system can be provided in the door and the couplingcan exist through the doorsill, for example. This eliminates the needfor wires to pass through the door interface and greatly simplifies theassembly and installation of doors. It also greatly reduces warrantyrepairs caused by the constant movement of wires at the door and carbody interface.

3.4 Blind Spot Monitor

Many accidents are caused by a driver executing a lane change when thereis another vehicle in his blind spot. As a result, several firms aredeveloping blind spot monitors based on radar, optics, or passiveinfrared, to detect the presence of a vehicle in the driver's blind spotand to warn the driver should he attempt such a lane change. These blindspot monitors are typically placed on the outside of the vehicle near oron the side rear view mirrors. Since the device is exposed to rain,salt, snow etc., there is a reliability problem resulting from the needto seal the sensor and to permit wires to enter the sensor and also thevehicle. Special wire, for example, should be used to prevent water fromwicking through the wire. These problems as well as similar problemsassociated with other devices which require electric power and which areexposed to the environment, such as forward-mounted airbag crashsensors, can be solved utilizing an inductive coupling techniques ofthis invention.

3.5 Truck-to-Trailer Power and Information Transfer

A serious source of safety and reliability problems results from theflexible wire connections that are necessary between a truck and atrailer. The need for these flexible wire connections and theirassociated connector problems can be eliminated using the inductivecoupling techniques of this invention. In this case, the mere attachmentof the trailer to the tractor automatically aligns an inductive pickupdevice on the trailer with the power lines imbedded in the fifth wheel,for example.

3.6 Wireless Switches

Switches in general do not consume power and therefore they can beimplemented wirelessly according to the teachings of this invention inmany different modes. For a simple on-off switch, a one bit RFID tagsimilar to what is commonly used for protecting against shoplifting instores with a slight modification can be easily implemented. The RFIDtag switch would contain its address and a single accessible bitpermitting the device to be interrogated regardless of its location inthe vehicle without wires. A SAW-based switch as disclosed elsewhereherein can also be used and interrogated wirelessly.

As the switch function becomes more complicated, additional power may berequired and the options for interrogation become more limited. For acontinuously varying switch, for example the volume control on a radio,it may be desirable to use a more complicated design where an inductivetransfer of information is utilized. On the other hand, by usingmomentary contact switches that would set the one bit on only while theswitch is activated and by using the duration of activation, volumecontrol type functions can still be performed even though the switch isremote from the interrogator.

This concept then permits the placement of switches at arbitrarylocations anywhere in the vehicle without regard to the placement ofwires. Additionally, multiple switches can be easily used to control thesame device or a single switch can control many devices.

For example, a switch to control the forward and rearward motion of thedriver seat can be placed on the driver door-mounted armrest andinterrogated by an RFID reader or SAW interrogator located in theheadliner of the vehicle. The interrogator periodically monitors allRFID or SAW switches located in the vehicle which may number over 100.If the driver armrest switch is depressed and the switch bit is changedfrom 0 to 1, the reader knows based on the address or identificationnumber of the switch that the driver intends to operate his seat in aforward or reverse manner. A signal can then be sent over the inductivepower transfer line to the motor controlling the seat and the motor canthus be commanded to move the seat either forward based on one switch IDor backward based on another switch ID. Thus, the switch in the armrestcould actually contain two identification RFIDs or SAW switches, one forforward movement of seat and one for rearward movement of the seat. Assoon the driver ceases operating the switch, the switch state returns to0 and a command is sent to the motor to stop moving the seat. The RFIDor SAW device can be passive or active.

By this process as taught by this invention, all of the 100 or soswitches and other simple sensors can become wireless devices and vastlyreduce the number of wires in a vehicle and increase the reliability andreduce warranty repairs. One such example is the switch that determineswhether the seatbelt is fastened which can now be a wireless switch.

3.7 Wireless Lights

In contrast to switches, lights require power. The power requiredgenerally exceeds that which can be easily transmitted by RF orcapacitive coupling. For lights to become wireless, therefore, inductivecoupling or equivalent can be required. Now, however, it is no longernecessary to have light sockets, wires and connectors. Each light bulbcould be outfitted with an inductive pickup device and a microprocessor.The microprocessor can listen to the information coming over theinductive pickup line, or wirelessly, and when it recognizes itsaddress, it activates an internal switch which turns on the light. Ifthe information is transferred wirelessly, the RFID switch described insection 1.4.4 above can be used. The light bulb becomes a totallysealed, self-contained unit with no electrical connectors or connectionsto the vehicle. It is automatically connected by mounting in a holderand by its proximity, which can be as far away as several inches, to theinductive power line. It has been demonstrated that power transferefficiencies of up to about 99 percent can be achieved by this systemand power levels exceeding about 1 kW can be transferred to a deviceusing a loosely coupled inductive system described above.

This invention therefore considerably simplifies the mounting of lightsin a vehicle since the lights are totally self-contained and not pluggedinto the vehicle power system. Problems associated with sealing thelight socket from the environment disappear vastly simplifying theinstallation of headlights, for example, into the vehicle. The skin ofthe vehicle need not contain any receptacles for a light plug andtherefore there is no need to seal the light bulb edges to prevent waterfrom entering behind the light bulb. Thus, the reliability of vehicleexterior lighting systems is significantly improved. Similarly, the easewith which light bulbs can be changed when they burn out is greatlysimplified since the complicated mechanisms for sealing the light bulbinto the vehicle are no longer necessary. Although headlights werediscussed, the same principles apply to all other lights mounted on avehicle exterior.

Since it is contemplated that the main power transfer wire pair willtravel throughout the automobile in a single branched loop, severallight bulbs can be inductively attached to the inductive wire powersupplier by merely locating a holder for the sealed light bulb within afew inches of the wire. Once again, no electrical connections arerequired.

Consider for example the activation of the right turn signal. Themicroprocessor associated with the turn switch on the steering column isprogrammed to transmit the addresses of the right front and rear turnlight bulbs to turn them on. A fraction of a second later, themicroprocessor sends a signal over the inductive power transfer line, orwirelessly, to turn the light bulbs off. This is repeated for as long asthe turn signal switch is placed in the activation position for a rightturn. The right rear turn signal light bulb receives a message with itsaddress and a bit set for the light to be turned on and it responds byso doing and similarly, when the signal is received for turning thelight off. Once again, all such transmissions occur over a single powerand information inductive line and no wire connections are made to thelight bulb. In this example, all power and information is transferredinductively.

3.8 Keyless Entry

The RFID technology is particularly applicable to keyless entry. Insteadof depressing a button on a remote vehicle door opener, the owner ofvehicle need only carry an RFID card in his pocket. Upon approaching thevehicle door, the reader located in the vehicle door, activates thecircuitry in the RFID card and receives the identification number,checks it and unlocks the vehicle if the code matches. It can even openthe door or trunk based on the time that the driver stands near the dooror trunk. Simultaneously, the vehicle now knows that this is driver No.3, for example, and automatically sets the seat position, headrestposition, mirror position, radio stations, temperature controls and allother driver specific functions including the positions of the petals toadapt the vehicle to the particular driver. When the driver sits in theseat, no ignition key is necessary and by merely depressing a switchwhich can be located anywhere in the vehicle, on the armrest forexample, the vehicle motor starts. The switch can be wireless and thereader or interrogator which initially read the operator's card can beconnected inductively to the vehicle power system.

U.S. Pat. No. 5,790,043 describes the unlocking of a door based on atransponder held by a person approaching the door. By adding thefunction of measuring the distance to the person, by use of thebackscatter from the transponder antenna for example, the distance fromthe vehicle-based transmitter and the person can be determined and thedoor opened when the person is within 5 feet, for example, of the dooras discussed elsewhere herein.

Using the RFID switch discussed above, for example, the integration ofthe keyless entry system with the tire monitor and all other similardevices can be readily achieved.

3.9 In-Vehicle Mesh Network, Intra-Vehicle Communications

The use of wireless networks within a vehicle has been discussedelsewhere herein. Of particular interest here is the use of a meshnetwork (or mesh) wherein the various wireless elements are connectedvia a mesh such that each device can communicate with each other tothereby add information that might aid a particular node. In thesimplest case, nodes on the mesh can merely aid in the transfer ofinformation to a central controller. In more advanced cases, thetemperature monitored by one node can be used by other nodes tocompensate for the effects of temperature on the node operation. Inanother case, the fact that a node has been damaged or is experiencingacceleration can be used to determine the extent of and to forecast theseverity of an accident. Such a mesh network can operate in the discretefrequency or in the ultra wideband mode.

3.10 Road Conditioning Sensing—Black Ice Warning

A frequent cause of accidents is the sudden freezing of roadways orbridge surfaces when the roadway is wet and temperatures are nearfreezing. Sensors exist that can detect the temperature of the roadsurface within less than one degree either by direct measurement or bypassive IR. These sensors can be mounted in locations on the vehiclewhere they have a clear view of the road and thus they are susceptibleto assault from rain, snow, ice, salt etc. The reliability of connectingthese sensors into the vehicle power and information system is thuscompromised. Using the teachings of this invention, black ice warningsensors, for example, can be mounted on the exterior of the vehicle andcoupled into the vehicle power and information system inductively, thusremoving a significant cause of failure of such sensors. Also the use ofappropriate cameras and sensors along with multispectral analysis ofroad surfaces can be particularly useful to discover icing.

Similar sensors can also used to detect the type of roadway on which thecar is traveling. Gravel roads, for example, have typically a lowereffective coefficient of friction than do concrete roads. Knowledge ofthe road characteristics can provide useful information to the vehiclecontrol system and, for example, warn the driver when the speed drivenis above what is safe for the road conditions, including the particulartype of roadway.

3.11 Antennas Including Steerable Antennas

As discussed above, the antennas used in the systems disclosed hereincan contribute significantly to the operation of the systems. In onecase, a silicon or gallium arsenide (for higher frequencies) element canbe placed at an antenna to process the returned signal as needed. Highgain antennas such as the yagi antenna or steerable antennas such aselectronically controllable (or tunable) dielectric constant phasedarray antennas are also contemplated. For steerable antennas, referenceis made to U.S. Pat. No. 6,452,565 “Steerable-beam multiple-feeddielectric resonator antenna”. Also contemplated, in addition to thosediscussed above, are variable slot antennas and Rotman lenses. All ofthese plus other technologies go under the heading of smart antennas andall such antennas are contemplated herein.

The antenna situation can be improved as the frequency increases.Currently, SAW devices are difficult to make that operate much aboveabout 2.4 GHz. It is expected that as lithography systems improve thateventually these devices will be made to operate in the higher GHz rangepermitting the use of antennas that are even more directional.

3.12 Other Miscellaneous Sensors

Many new sensors are now being adapted to an automobile to increase thesafety, comfort and convenience of vehicle occupants. Each of thesensors currently requires separate wiring for power and informationtransfer. Under the teachings of this invention, these separate wirescan become unnecessary and sensors could be added at will to theautomobile at any location within a few inches of the inductive powerline system or, in some cases, within range of an RF interrogator. Evensensors that were not contemplated by the vehicle manufacturer can beadded later with a software change to the appropriate vehicle CPU asdiscussed above.

Such sensors include heat load sensors that measure the sunlight comingin through the windshield and adjust the environmental conditions insidethe vehicle or darken the windshield to compensate. Seatbelt sensorsthat indicate that the seatbelt is buckled and the tension oracceleration experienced by the seatbelt can now also use RFID and/orSAW technology as can low power microphones. Door-open or door-ajarsensors also can use the RFID and/or SAW technology and would not needto be placed near an inductive power line. Gas tank fuel level and otherfluid level sensors which do not require external power and are nowpossible thus eliminating any hazard of sparks igniting the fuel in thecase of a rear impact accident which ruptures the fuel tank, forexample.

Capacitive proximity sensors that measure the presence of a life formwithin a few meters of the automobile can be coupled wirelessly to thevehicle. Cameras or other vision or radar or lidar sensors that can bemounted external to the vehicle and not require unreliable electricalconnections to the vehicle power system permitting such sensors to betotally sealed from the environment are also now possible. Such sensorscan be based on millimeter wave radar, passive or active infrared, oroptical or any other portion of the electromagnetic spectrum that issuitable for the task. Radar, passive sound or ultrasonic backup sensorsor rear impact anticipatory sensors also are now feasible withsignificantly greater reliability.

The use of passive audio requires additional discussion. One or moredirectional microphones aimed from the rear of the vehicle can determinefrom tire-produced audio signals, for example, that a vehicle isapproaching and might impact the target vehicle which contains thesystem. The target vehicle's tires as well as those to the side of thetarget vehicle will also produce sounds which need to be cancelled outof the sound from the directional microphones using well-known noisecancellation techniques. By monitoring the intensity of the sound incomparison with the intensity of the sound from the target vehicle's owntires, a determination of the approximate distance between the twovehicles can be made. Finally, a measurement of the rate of change insound intensity can be used to estimate the time to collision. Thisinformation can then be used to pre-position the headrest, for example,or other restraint device to prepare the occupants of the target vehiclefor the rear end impact and thus reduce the injuries therefrom. Asimilar system can be used to forecast impacts from other directions. Insome cases, the microphones will need to be protected in a manner so asto reduce noise from the wind such as with a foam protection layer. Thissystem provides a very inexpensive anticipatory crash system.

Previously, the use of radio frequency to interrogate an RFID tag hasbeen discussed. Other forms of electromagnetic radiation are possible.For example, an infrared source can illuminate an area inside thevehicle and a pin diode or CMOS camera can receive reflections fromcorner cube or dihedral corner (as more fully descried below) reflectorslocated on objects that move within the vehicle. These objects wouldinclude items such as the seat, seatback, and headrest. Through thistechnique, the time of flight, by pulse or phase lock loop technologies,can be measured or modulated IR radiation and phase measurements can beused to determine the distance to each of the corner cube or dihedralcorner reflectors.

The above discussion has concentrated on applications primarily insideof the vehicle (although mention is often made of exterior monitoringapplications). There are also a significant number of applicationsconcerning the interaction of a vehicle with its environment. Althoughthis might be construed as a deviation from the primary premise of thisinvention, which is that the device is either powerless in the sensethat no power is required other than perhaps that which can be obtainedfrom a radio frequency signal or a powered device and where the power isobtained through induction coupling, it is encompassed within theinvention.

When looking exterior to the vehicle, devices that interact with thevehicle may be located sufficiently far away that they will requirepower and that power cannot be obtained from the automobile. In thediscussion below, two types of such devices will be considered, thefirst type which does not require infrastructure-supplied power and thesecond which does.

A rule of thumb is that an RFID tag of normal size that is located morethan about a meter away from the reader or interrogator must have aninternal power source. Exceptions to this involve cases where the onlyinformation that is transferred is due to the reflection off of a radarreflector-type device and for cases where the tag is physically larger.For those cases, a purely passive RFID can be five and sometimes moremeters away from the interrogator. Nevertheless, we shall assume that ifthe device is more than a few meters away that the device must containsome kind of power supply.

An interesting application is a low-cost form of adaptive cruise controlor forward collision avoidance system. In this case, a purely passiveRFID tag could be placed on every rear license plate in a particulargeographical area, such as a state. The subject vehicle would containtwo readers, one on the forward left side of the vehicle and one on theforward right side. Upon approaching the rear of a car having the RFIDlicense plate, the interrogators in the vehicle would be able todetermine the distance, by way of reflected signal time of flight, fromeach reader to the license plate transducer. If the license plate RFIDis passive, then the range is limited to about 5 meters depending on thesize of the tag. Nevertheless, this will be sufficient to determine thatthere is a vehicle in front of or to the right or left side of thesubject vehicle. If the relative velocity of the two vehicles is suchthat a collision will occur, the subject vehicle can automatically haveits speed altered so as to prevent the collision, typically a rear endcollision. Alternately, the front of the vehicle can have twospaced-apart tags in which case, a single interrogator could suffice.

The following explanation is from Prof G. Khlopov of the Institute ofRadioPhysics and Electronics of National Academy of Science of Ukraine.

General

The dihedral corner reflector is widely used as a standard target forcalibration of radar. Such reflector consists of two planes bydimensions a×b that cross at right angles as shown in FIGS. 84 and 84A.

In the general case, the properties of such a target are described byscattering pattern power (angle dependence of power reflected), value ofradar cross section (RCS), which determines its radar visibility anddependence of RCS on polarization of the incident wave.

Scattering Power Pattern

In the azimuth plane the RCS for horizontal −σ_(xx)(φ) and verticalσ_(yy)(φ) polarizations is determined by the expression (1), which isvalid for a quite large reflector in comparison with the radarwavelength a>>λ

$\begin{matrix}{{{\sigma_{xx}(\varphi)} = {{\sigma_{yy}(\varphi)} = {2\sigma_{m}{\begin{matrix}\begin{matrix}{{\cos( {\frac{\pi}{4} + {\varphi }} )} -} \\{\frac{1}{2}{\cos( {\frac{\pi}{4} + \varphi^{2}} )}\frac{\sin\lbrack {{ka}\;{\sin( {\frac{\pi}{4} - {\varphi }} )}} \rbrack}{{ka}\;{\sin( {\frac{\pi}{4} - {\varphi }} )}} \times}\end{matrix} \\{\mathbb{e}}^{{- j}\;\frac{ka}{2}{\cos{({\frac{\pi}{4} + {\varphi }})}}}\end{matrix}}^{2}}}},} & (1)\end{matrix}$

where φ is the azimuth angle

${( {{- \frac{\pi}{4}} \leq \varphi \leq \frac{\pi}{4}} ),{\sigma_{m} = {8{\pi( \frac{ab}{\lambda} )}^{2}\text{-}{value}\mspace{14mu}{of}\mspace{14mu}{RCS}\mspace{14mu}{in}\mspace{14mu}{the}\mspace{14mu}{boresight}\mspace{14mu}{of}\mspace{14mu}{scattering}\mspace{14mu}{pattern}\mspace{14mu}( {\varphi = 0} )}},\mspace{14mu}{k = {\frac{2\pi}{\lambda}\text{-}{wave}\mspace{14mu}{{number}.}}}}\mspace{14mu}$For example, the scattering pattern is shown for a=6.42λ in FIG. 85,which slightly depends on value of a/λ

As shown, the scattering pattern is approximately of 30 degrees width atlevel −3 dB (independently of value a/λ for a≧λ) and has two side lobesat −3 dB level.

In the vertical plane (along Y axis), the scattering pattern isdetermined by the expression

$\begin{matrix}{{{\sigma_{xx}(\theta)} = {{\sigma_{yy}(\theta)} = {8{{\pi( \frac{ab}{\lambda} )}^{2}\lbrack \frac{\sin\lbrack {{kb}\;\sin\;\theta} \rbrack}{{kb}\;\sin\;\theta} \rbrack}^{2}}}},} & (2)\end{matrix}$

where θ—elevation angle.

The shape of scattering pattern in the vertical plane is presented inFIG. 86 and its width is approximately 25λ/b degrees at level −3 dB.

Radar Cross Section

The RCS of dihedral corner reflector in boresight of scattering patternpower (θ=φ=0) is described by the formulas when its dimensions are morethan radar wavelength a,b≧λ. When the incidence field is polarized inthe principal planes (horizontal and vertical planes), the RCS isdetermined by the expression

$\begin{matrix}{{\sigma_{xx}(\theta)} = {{\sigma_{yy}(\theta)} = {8{\pi( \frac{ab}{\lambda} )}^{2}}}} & (3)\end{matrix}$

Polarization Properties.

When the plane of polarization of incidence field does not coincide withthe principal planes of dihedral corner and is inclined at the angleα—FIG. 87, then reflector scattered the incident field also at theorthogonal polarization. In other words the total power reflected can berepresented as the sum of two components—vertical and horizontal,according to the following expression (for θ=0)

$\begin{matrix}{{{\sigma_{Ver}( {\alpha,\varphi} )} = {2\sigma_{m}\cos^{2}2{\alpha \cdot {\cos^{2}( {\frac{\pi}{4} + {\varphi }} )}}}},{{\sigma_{Hor}( {\alpha,\varphi} )} = {2\sigma_{m}\sin^{2}2{\alpha \cdot {{\cos^{2}( {\frac{\pi}{4} + {\varphi }} )}.}}}}} & (4)\end{matrix}$

For this reason, the total vector of the reflected field is linearpolarized and its plane is rotated on angle β=2α relatively to theprincipal plane of dihedral corner—FIG. 87.

This property is widely used in microwave devices for rotating of linearpolarization on angle 90 deg, when the plane of polarization ofincidence field is oriented at 45 deg. to the principal plane of thecorner—FIG. 88.

Nevertheless, it is not only the possibility of polarization angles thatare produced. There are no limits on the rotation angle and, forexample, it is possible to obtain the rotation angle β=±45 deg when theangle α is equal to ±22.5 deg.

Application of Dihedral Corner Reflector in Development of Radar PrecisePositioning System of Vehicles

In the project “Radar development for Precise Positioning System ofVehicles” developed jointly with Orion Company (Kiev, Ukraine) in theinterests of the current assignee, the principal problem is to selectsignals, scattered from corner reflectors S1 and S2 (FIG. 88), which arelocated along the road in a special way. Actually, such signals usuallyare masked by clutter from terrain because any objects may appear withinthe radar beam (buildings, constructions, trees etc.).

The simplest way to solve the problem is to provide a largesignal-to-clutter ratio that is quite hard in the case underconsideration. As the research shows, most anthropogenic objects(buildings, constructions etc.) are of spatial distributed type, theirdimensions are essentially larger than the diameter of the radar beamand its RCS in millimeter wave band is about tens of m². The RCS oftraditional trihedral corner reflector is equal to σ₀=4πa⁴/3λ² (a—sizeof edge, λ—wavelength) and it is practically impossible to providevalues of RCS more than 50-100 m² in 4 mm millimeter wavelengths becauseof the following reasons:

-   -   the necessary dimensions of corner reflector are quite        large≈200×200×200 mm;    -   the necessary accuracy of producing is too high—angle between        the corner edges must be equal 90±0.1 deg.

That's why the application of usual trihedral corner reflectors cannotstand out over the background of the clutter. On the other hand, theapplication of dihedral angle reflector can provide an effectivepolarization selection of such reflector on the background of clutterfrom terrain.

As is well known for composite targets, including anthropogenic objects(buildings, constructions, background clutters etc.), the main reflectedpower is concentrated on co-polarized component, i.e. plane ofpolarization of which is coincident with the polarization of incidentwave. For this reason, it is possible to decrease their influence if thereflector provides rotation of polarization plane of scattered field at90 degrees. In that case the radar receiver also must be turned onreception of cross-polarized component that provides significantdecreasing of clutter power.

Such a property may be provided by using a dihedral corner reflector,which is oriented at 45 degrees relative to the plane of polarization ofthe incident field—FIG. 89.

When the incident field E_(in) is transformed to the orthogonalpolarized reflected field—E_(s), on which the RCS of composite targetsusually does not exceed 0.01-0.015 m².

Therefore, the dihedral corner reflector enables the signal-to-clutterratio more than 10 dB (a=30 mm, b=90 mm) and this is enough to providereliable selection of signals from the reflectors on the clutterbackground. As a result, the reception of reflected signals oncross-polarized component also provides high isolation betweentransmitter and receiver that improves signal-to-noise ratio for CW FMradar.

This leads to a novel addition or substitution to putting an RFID tagonto a license plate is to emboss the license plate or otherwise attachto it or elsewhere on the vehicle a corner cube or dihedral cornerreflector which can yield a bright reflection from a radar or ladar(laser radar) transmitter from a following vehicle, for example.Further, the reflector can be designed to rotate the polarization of abeam by 90 degrees, thus the potential problem of the receiver beingblinded by another vehicle's system is reduced. Additionally, areflector can be designed as described above to reflect a polarized beamfrom a non-polarized beam or better to rotate a polarized beam throughan arbitrary angle. In this manner, some information about the vehiclesuch as its mass class can be conveyed to the interrogating vehicle. Apolarization on only 0 degrees can signify a passenger car, only 90degrees an SUV or other large passenger vehicle or pickup truck, 45degrees a small truck, both 0 and 45 degrees (using two reflectors) alarger truck, 45 and 90 degrees a larger truck etc. yielding 7 or moreclassifications. Thus using a very low cost reflector, a great deal ofinformation can be conveyed including the range to the vehicle based ontime-of-flight or phase angle comparison if the transmitted beam ismodulated. Noise or pseudo-noise modulated radar would also beapplicable as a modulation based system for distance measurement.

Additions to an RFID-based system that can be used alone or along withthe reflector system discussed above include the addition of an energyharvesting system such as solar power or power from vibrations. Thus thetag can start out as a pure passive tag providing up to about 10 metersrange and grow to an active tag providing a 30 or more meter range. Withthe use of RFID, a great deal of additional information can betransmitted such as the vehicle weight, license plate number, tolling IDetc. Once a tire pressure interrogator as discussed above is on thevehicle, the cost to add one or more license plate interrogatingantennas is small and the cost addition to a license plate can be as lowas 1-5 US dollars. Since no electrical connection need be made to thevehicle, the installation cost is no more than for an ordinary licenseplate.

An alternate approach is to visually scan license plates using an imagersuch as a camera. An infrared imager and a source of infraredillumination can be used. Using such a system, the characters (numbersand letters) can be read and if the license plate-issuing authority hascoded the properties (type of vehicle, weight, etc.) into thesecharacters, a vehicle can identify those properties of a vehicle that itmay soon impact and that information can be a factor in the vehiclecontrol algorithm or restraint deployment decision.

Systems are under development that will permit an automobile todetermine its absolute location on the surface of the earth. Thesesystems are being developed in conjunction with intelligenttransportation systems. Such location systems are frequently based ondifferential GPS (DGPS). One problem with such systems is that theappropriate number of GPS satellites is not always within view of theautomobile. For such cases, it is necessary to have an earth-basedsystem which will provide the information to the vehicle permitting itto absolutely locate itself within a few centimeters. One such systemcan involve the use of RFID tags placed above, adjacent or below thesurface of the highway.

For the cases where the RFID tags are located more than a few metersfrom the vehicle, a battery or other poser source will probably berequired and this will be discussed below. For the systems withoutbatteries, such as placing the RFID tag in the concrete, with tworeaders located one on each side of the vehicle, the location of the tagembedded in the concrete can be precisely determine based on the time offlight of the radar pulse from the readers to the tag and back. Usingthis method, the precise location of the vehicle relative to a tagwithin a few centimeters can be readily determined and since theposition of the tag will be absolutely known by virtue of an in-vehicleresident digital map, the position of the vehicle can be absolutelydetermined regardless of where the vehicle is. For example, if thevehicle is in a tunnel, then it will know precisely its location fromthe RFID pavement embedded tags. Note that the polarization rotationreflector discussed above will also perform this task excellently.

It is also possible to determine the relative velocity of the vehiclerelative to the RFID tag or reflector using the Doppler Effect based onthe reflected signals. For tags located on license plates or elsewhereon the rear of vehicles, the closing velocity of the two vehicles can bedetermined and for tags located in or adjacent to the highway pavement,the velocity of the vehicle can be readily determined. The velocity canin both cases be determined based on differentiating two distancemeasurements.

In many cases, it may be necessary to provide power to the RFID tagsince the distance to the vehicle will exceed a few meters. This iscurrently being used in reverse for automatic tolling situations wherethe RFID tag is located on the vehicle and interrogated using readerslocated at the toll both.

When the RFID tag to be interrogated by vehicle-mounted readers is morethan a few meters from the vehicle, the tag in many cases must besupplied with power. This power can come from a variety of sourcesincluding a battery which is part of the device, direct electricalconnections to a ground wire system, solar batteries, generators thatgenerate power from vehicle or component vibration, other forms ofenergy harvesting or inductive energy transfer from a power line.

For example, if an RFID tag were to be placed on a light post indowntown Manhattan, sufficient energy could be obtained from aninductive pickup from the wires used to power the light to recharge abattery in the RFID. Thus, when the lights are turned on at night, theRFID battery could be recharged sufficiently to provide power foroperation 24 hours a day. In other cases, a battery or ultracapacitorcould be included in the device and replacement or recharge of thebattery would be necessitated periodically, perhaps once every twoyears.

An alternate approach to having a vehicle transmit a pulse to the tagand wait for a response, would be to have the tag periodically broadcasta few waves of information at precise timing increments. Then, thevehicle with two receivers could locate itself accurately relative tothe earth-based transmitter.

For example, in downtown Manhattan, it would be difficult to obtaininformation from satellites that are constantly blocked by tallbuildings. Nevertheless, inexpensive transmitters could be placed on avariety of lampposts that would periodically transmit a pulse to allvehicles in the vicinity. Such a system could be based on a broadbandmicropower impulse radar system as disclosed in several U.S. patents.Alternately, a narrow band signal can be used.

Once again, although radar type microwave pulses have been discussed,other portions of the electromagnetic spectrum can be utilized. Forexample, a vehicle could send a beam of modulated infrared towardinfrastructure-based devices such as poles which contain corner orpolarization modifying reflectors. The time of flight of IR radiationfrom the vehicle to the reflectors can be accurately measured and sincethe vehicle would know, based on accurate maps, where the reflector islocated, there is the little opportunity for an error.

The invention is also concerned with wireless devices that containtransducers. An example is a temperature transducer coupled withappropriate circuitry which is capable of receiving power eitherinductively or through radio frequency energy transfer or even, and somecases, capacitively. Such temperature transducers may be used to measurethe temperature inside the passenger compartment or outside of thevehicle. They also can be used to measure the temperature of somecomponent in the vehicle, e.g., the tire. A distinctive feature of someembodiments of this invention is that such temperature transducers arenot hard-wired into the vehicle and do not rely solely on batteries.Such temperature sensors have been used in other environments such asthe monitoring of the temperature of domestic and farm animals forhealth monitoring purposes.

Upon receiving power inductively or through the radio frequency energytransfer, the temperature transducer conducts its temperaturemeasurement and transmits the detected temperature to a process orcentral control module in the vehicle.

The wireless communication within a vehicle can be accomplished inseveral ways. The communication can be through the same path thatsupplies power to the device, or it can involve the transmission ofwaves that are received by another device in the vehicle. These wavescan be either electromagnetic (radio frequency, microwave, infrared,etc) or ultrasonic. If electromagnetic, they can be sent using a varietyof protocols such as CDMA, FDMA, TDMA or ultrawideband (see, e.g.,Hiawatha Bray, “The next big thing is actually ultrawide”, Boston Globe,Jun. 25, 2004).

Many other types of transducers or sensors can be used in this manner.The distance to an object from a vehicle can be measured using a radarreflector type RFID (Radio Frequency Identification) tag which permitsthe distance to the tag to be determined by the time of flight of radiowaves. Another method of determining distance to an object can bethrough the use of ultrasound wherein the device is commanded to emit anultrasonic burst and the time required for the waves to travel to areceiver is an indication of the displacement of the device from thereceiver.

Although in most cases the communication will take place within thevehicle, and some cases such as external temperature transducers or tirepressure transducers, the source of transmission will be located outsideof the compartment of the vehicle.

A discussion of RFID technology including its use for distancemeasurement is included in the RFID Handbook, by Klaus Finkenzeller,John Wiley & Sons, New York 1999.

In one simple form, the invention can involve a single transducer andsystem for providing power and receiving information. An example of sucha device would be an exterior temperature monitor which is placedoutside of the vehicle and receives its power and transmits itsinformation through the windshield glass. At the other extreme, a pairof parallel wires carrying high frequency alternating current can travelto all parts of the vehicle where electric power is needed. In thiscase, every device could be located within a few inches of this wirepair and through an appropriately designed inductive pickup system, eachdevice receives the power for operation inductively from the wire pair.A system of this type which is designed for use in powering vehicles isdescribed in several U.S. patents listed above.

In this case, all sensors and actuators on the vehicle can be powered bythe inductive power transfer system. The communication with thesedevices could either be over the same system or, alternately, could betake place via RF, ultrasound, infrared or other similar communicationsystem. If the communication takes place either by RF or over amodulated wire system, a protocol such as the Bluetooth™ or Zigbeeprotocol can be used. Other options include the Ethernet and token ringprotocols.

The above system technology is frequently referred to as loosely coupledinductive systems. Such systems have been used for powering a vehicledown a track or roadway but have not been used within the vehicle. Theloosely coupled inductive system makes use of high frequency (typically10,000 Hz) and resonant circuits to achieve a power transfer approaching99 percent efficiency. The resonant system is driven using a switchingamplifier. As discussed herein, this is believed to be the first exampleof a high frequency power system for use within vehicles.

Every device that utilizes the loosely coupled inductive system wouldcontain a microprocessor and thus would be considered a smart device.This includes every light, switch, motor, transducer, sensor etc. Eachdevice could have an address and would respond only to informationcontaining its address.

It is now contemplated that the power systems for next generationautomobiles and trucks will change from the current standard of 12 voltsto a new standard of 42 volts. The power generator or alternator in suchvehicles will produce alternating current and thus will be compatiblewith the system described herein wherein all power within the vehiclewill be transmitted using AC.

It is contemplated that some devices will require more power than can beobtained instantaneously from the inductive, capacitive or radiofrequency source. In such cases, batteries, capacitors orultra-capacitors may be used directly associated with a particulardevice to handle peak power requirements. Such a system can also be usedwhen the device is safety critical and there is a danger of disruptionof the power supply during a vehicle crash, for example. In general, thebattery or capacitor would be charged when the device is not beingpowered.

In some cases, the sensing device may be purely passive and require nopower. One such example is when an infrared or optical beam of energy isreflected off of a passive reflector to determine the distance to thatreflector. Another example is a passive reflective RFID tag.

As noted above, several U.S. patents describe arrangements formonitoring the pressure inside a rotating tire and to transmit thisinformation to a display inside the vehicle. A preferred approach formonitoring the pressure within a tire is to instead monitor thetemperature of the tire using a temperature sensor and associated powersupplying circuitry as discussed above and to compare that temperatureto the temperature of other tires on the vehicle, as discussed above.When the pressure within a tire decreases, this generally results in thetire temperature rising if the vehicle load is being carried by thattire. In the case where two tires are operating together at the samelocation such as on a truck trailer, just the opposite occurs. That is,the temperature of the fully inflated tire can increase since it is nowcarrying more load than the partially inflated tire.

4. Summary

As stated at the beginning this application is one in a series ofapplications covering safety and other systems for vehicles and otheruses. The disclosure herein goes beyond that needed to support theclaims of the particular invention that is being claimed herein. This isnot to be construed that the inventor is thereby releasing the unclaimeddisclosure and subject matter into the public domain. Rather, it isintended that patent applications have been or will be filed to coverall of the subject matter disclosed above.

The inventions described above are, of course, susceptible to manyvariations, combinations of disclosed components, modifications andchanges, all of which are within the skill of the art. It should beunderstood that all such variations, modifications and changes arewithin the spirit and scope of the inventions and of the appendedclaims. Similarly, it will be understood that applicant intends to coverand claim all changes, modifications and variations of the examples ofthe preferred embodiments of the invention herein disclosed for thepurpose of illustration which do not constitute departures from thespirit and scope of the present invention as claimed.

Although several preferred embodiments are illustrated and describedabove, there are possible combinations using other geometries, sensors,materials and different dimensions for the components that perform thesame functions. This invention is not limited to the above embodimentsand should be determined by the following claims.

1. A tire monitoring assembly for association with a movable tire of avehicle, said tire having flexible side walls and a flexible tread, theassembly adapted to provide information about a property of said tire,the assembly comprising: a power generating system adapted to be coupledwith said tire to generate energy from movement of said tire; and acircuit coupled to said power generating system and including an energystorage device, said circuit being operable in an active mode when saidtire moves and in a passive mode when said tire is not moving, saidcircuit being arranged to provide the information about the property ofsaid tire and including at least one wireless transmission component fortransmitting a signal relating to the property of said tire, said atleast one wireless transmission component requiring energy to transmitthe signal relating to the tire property, said circuit being constructedand arranged such that in the active mode, said power generating systemgenerates energy which is used by said circuit or stored in said energystorage device, said circuit being constructed and arranged such that inthe passive mode, said circuit receives power from a signal received bysaid circuit to enable and cause said at least one wireless transmissioncomponent to transmit the signal relating to the property of said tire,when: 1) said energy storage device does not contain sufficient energyto power said circuit, and 2a) the property of said tire is above athreshold, wherein said at least one wireless transmission componentdoes not transmit a signal relating to the property of said tire whenthe property is not above the threshold, or 2b) the property of saidtire is below a threshold, wherein said at least one wirelesstransmission component does not transmit a signal relating to theproperty of said tire when the property is not below the threshold. 2.The assembly of claim 1, wherein said at least one wireless transmissioncomponent is arranged to receive a signal for powering said circuit inthe passive mode.
 3. The assembly of claim 2, wherein the property ofsaid tire is pressure of said tire and said circuit includes a pressuresensor for generating information about the pressure in said tire,transmission of a signal from said at least one wireless transmissioncomponent in the passive mode being indicative of a pressure in saidtire below the pressure threshold.
 4. The assembly of claim 1, whereinsaid at least one wireless transmission component is arranged to receivea signal for powering said circuit in the passive mode and said circuitincludes at least one sensor for generating or modifying a signalreceived by said at least one wireless transmission component as afunction of the property of said tire, the generated or modified signalthereby relating to the property of said tire.
 5. The assembly of claim1, wherein said tire comprises a flexible elastic substrate definingsaid side walls of said tire and said tread whereby said powergenerating system generates energy upon rotation of said tire.
 6. Theassembly of claim 1, wherein said power generating system is arranged togenerate energy upon deflection or flexure of said tire tread or saidside walls.
 7. The assembly of claim 1, wherein said circuit is arrangedto generate or modify a signal which enables a determination of theproperty of said tire and wirelessly transmit the signal along with anidentification of said tire via said at least one wireless transmissioncomponent.
 8. The assembly of claim 1, wherein the property of said tireis tire is temperature and/or pressure of said tire such that saidcircuit is arranged to measure the pressure and/or temperature of saidtire and wireless transmit the measured pressure and/or temperature viasaid at least one wireless transmission component.
 9. The assembly ofclaim 1, wherein said circuit is arranged to generate or modify a signalwhich enables acceleration or deformation of said tread when said tireis rotating to be determined.
 10. The assembly of claim 1, wherein saidcircuit includes at least one sensor arranged to generate or modify asignal which enables a determination of the property of said tire, saidat least one wireless transmission component being arranged towirelessly transmit the signal when energy available to said circuitexceeds an energy threshold.
 11. The assembly of claim 1, wherein saidcircuit includes at least one sensor arranged to generate or modify aplurality of signals which enable a determination of a plurality ofproperties of said tire, said at least one wireless transmissioncomponent being arranged to wirelessly transmit one or more of thesignals based on the amount of energy available to said circuit.
 12. Theassembly of claim 1, wherein said circuit includes at least one sensorarranged to measure or determine the property of said tire, said atleast one wireless transmission component being arranged to receive aninterrogation signal and cause said at least one sensor to generate areturn signal, said circuit further including a circulator arrangedbetween said at least one sensor and said at least one wirelesstransmission component to boost the return signal.
 13. The assembly ofclaim 1, wherein said circuit includes at least one sensor arranged tomodify a signal which enables a determination of a property of saidtire, said at least one wireless transmission component being arrangedto receive an interrogation signal and cause said at least one sensor tomodify the interrogation signal, said circuit further including acirculator arranged between said at least one sensor and said at leastone wireless transmission component to boost the interrogation signalbeing directed to said at least one sensor and the modifiedinterrogation signal being directed from said at least one sensor. 14.The assembly of claim 1, wherein said circuit includes at least onepressure sensor arranged to generate or modify a first signal whichenables a determination of pressure of said tire and at least oneadditional sensor arranged to generate or modify a second signal whichenables a determination of another property of said tire, said at leastone wireless transmission component being arranged to wirelesslytransmit the first signal when said circuit is in the passive mode andoptionally transmit the second signal when said circuit is in the activemode.
 15. The assembly of claim 1, wherein said circuit includes atleast one pressure sensor arranged to generate or modify a signal whichenables a determination of pressure of said tire, said at least onewireless transmission component being arranged to wirelessly transmitthe signal at different times spaced apart from one another an amount oftime dependent on the amount of energy available to said circuit. 16.The assembly of claim 1, wherein said power generating system comprisesa pad made from piezoelectric material and arranged to flex uponrotation of said tire, the flexing of said pad causing a charge toappears on opposite sides of said pad thereby creating a voltage whichcharges said energy storage device.
 17. The assembly of claim 16,wherein said pad is attached to an inner surface of said substrateadjacent to said tread.
 18. The assembly of claim 16, wherein said padincludes a plurality of layers of piezoelectric material.
 19. Theassembly of claim 16, wherein said pad comprises a plurality of sectionsof piezoelectric material joined together to form a belt stretchingaround an inner circumference of said substrate.
 20. The assembly ofclaim 1, wherein the property of said tire is pressure and said circuitincludes a pressure sensor arranged to generate or modify a signal whichenables a determination of pressure of said tire and apressure-activated switch interposed between said pressure sensor andsaid at least one wireless transmission component and having a closedposition only when pressure in said tire is below the threshold and saidcircuit is in the passive mode, the closed position of said switchenabling a signal relating to the pressure of said tire generated bysaid pressure sensor to be provided to said at least one wirelesstransmission component, said switch being in an open position when saidcircuit is in the active mode and when said circuit is in the passivemode and the pressure is not below the threshold.
 21. The assembly ofclaim 20, wherein said circuit further includes an additional switchinterposed between said pressure sensor and said at least one wirelesstransmission component and having a closed position only when saidcircuit is in the active mode, said additional switch having an openposition when said circuit is in the passive mode.
 22. The assembly ofclaim 20, wherein said pressure sensor is a pressure sensing diaphragmin communication with an interior of said tire such that when pressurein said tire is below the threshold, said diaphragm moves and causessaid switch to move into the closed position.
 23. The assembly of claim1, wherein said circuit includes a surface-acoustic-wave device or aradio-frequency identification device.
 24. The assembly of claim 1,wherein said circuit includes a sensor arranged to generate or modify asignal which enables a determination of the property of said tire and aswitch interposed between said sensor and said at least one wirelesstransmission component, said switch having a closed position when theproperty of said tire is below the threshold and said circuit is in thepassive mode and an open position when the property of said tire is notbelow the threshold, or said switch having a closed position when theproperty of said tire is above the threshold and said circuit is in thepassive mode and an open position when the property of said tire is notabove the threshold, the closed position of said switch enabling asignal relating to the property of said tire to be provided by saidsensor to said at least one wireless transmission component.
 25. Theassembly of claim 1, wherein the threshold is variable.
 26. The assemblyof claim 1, wherein said circuit includes at least one sensor arrangedto measure or determine the property of said tire, said at least onewireless transmission component being arranged to receive aninterrogation signal and cause said at least one sensor to generate areturn signal.
 27. The assembly of claim 1, wherein the property of saidtire is temperature and said circuit includes a temperature sensorarranged to generate or modify a signal which enables a determination oftemperature of said tire and a temperature-activated switch interposedbetween said temperature sensor and said at least one wirelesstransmission component and having a closed position only whentemperature in said tire is above the threshold and said circuit is inthe passive mode, the closed position of said switch enabling a signalrelating to the temperature of said tire generated by said temperaturesensor to be provided to said at least one wireless transmissioncomponent.
 28. The assembly of claim 27, wherein said temperature sensoris a diaphragm which expands with temperature in the interior of saidtire such that when temperature in said tire is above the threshold,said diaphragm expands and causes said switch to move into the closedposition.
 29. A method for monitoring a tire, comprising: arranging amonitoring system on the tire which generates or modifies a signal whichenables a determination of at least one property of the tire andprovides a wireless transmission of the generated or modified signal;generating energy to power the monitoring system from rotation of thetire; storing energy generated while the tire is rotating to power themonitoring system when the tire is not rotating; directing aninterrogation signal to the monitoring system to obtain in response, thewireless transmission of the signal generated or modified by themonitoring system; providing the monitoring system with an active modewhen the tire rotates and energy is being generated to enable themonitoring system to generate or modify the signal; providing themonitoring system with a passive mode when the tire is not rotating; andconstructing the monitoring system such that in the passive mode, themonitoring system receives power from a signal received by themonitoring system to enable the wireless transmission of the signalgenerated or modified by the monitoring system in response to theinterrogation signal directed to the monitoring system, when: 1) thereis insufficient stored energy to power the monitoring system, and 2a)the at least one property of the tire is above a threshold, wherein themonitoring system does not provide the wireless transmission of thesignal when the at least one property is not above the threshold, or 2b)the at least one property of the tire is below a threshold, wherein themonitoring system does not provide the wireless transmission of thesignal when the at least one property is not below the threshold. 30.The method of claim 29, wherein the step of arranging the monitoringsystem on the tire comprises attaching the monitoring system to a sidewall or tread of the tire.
 31. The method of claim 29, wherein the stepof generating energy to power the monitoring system from rotation of thetire comprises generating energy upon deflection or flexure of a tiretread or side walls of the tire.
 32. The method of claim 29, furthercomprising constructing the monitoring system to transmit the generatedor modified signal along with an identification of the tire.
 33. Themethod of claim 29, wherein the at least one property is pressure of thetire, temperature of the tire, and/or acceleration or deformation of atread of the tire when the tire is rotating.
 34. The method of claim 29,further comprising constructing the monitoring system to transmit thegenerated or modified signal in the passive mode whenever aninterrogation signal is received only when stored energy available tothe monitoring system exceeds an energy threshold.
 35. The method ofclaim 29, wherein the monitoring system generates or modifies aplurality of signals which enable a determination of a plurality ofproperties of the tire, further comprising constructing the monitoringsystem to select which of the plurality of signals to transmit based onthe amount of energy available to the monitoring system.
 36. The methodof claim 29, further comprising constructing the monitoring system totransmit the generated or modified signal at different times spacedapart from one another an amount of time dependent on the amount ofenergy available to the monitoring system.
 37. The method of claim 29,wherein the monitoring system includes a pressure sensor arranged togenerate or modify a signal which enables a determination of pressure ofthe tire and a wireless transmission component arranged to wirelesslytransmit the signal, further comprising arranging a pressure-activatedswitch between the pressure sensor and the wireless transmissioncomponent and which has a closed position only when pressure in the tireis below the pressure threshold and the monitoring system is in thepassive mode, the switch being in an open position when the monitoringsystem is in the active mode and when the monitoring system in thepassive mode and the pressure is not below the threshold.
 38. The methodof claim 37, further comprising arranging an additional switch betweenthe pressure sensor and the wireless transmission component and whichhas a closed position only when the monitoring system is in the activemode.
 39. A tire monitoring assembly for association with a movable tireof a vehicle, said tire having flexible side walls and a flexible tread,the assembly adapted to provide information about a property of saidtire, the assembly comprising: a power generating system arranged on orin said side walls to generate energy from rotation of said tire; and acircuit coupled to said power generating system and including an energystorage device, said power generating system generating energy when saidtire rotates and using the generated energy to power said circuit orstoring energy in said energy storage device, said circuit beingarranged to provide the information about the property of said tire andincluding at least one wireless transmission component for transmittinga signal relating to the property of said tire, said at least onewireless transmission component requiring energy to transmit the signalrelating to the tire property and being provided with energy by saidpower generating system or said energy storage device.